Collecting trace evidence containing trace elements is important to Forensic Scientists because of the value trace evidence has to the tail. Hair, paint, glass, fibers, soil and other particulate matter are examined closely by the Forensic Investigator using high tech instruments such as scanning electron microscope, polarized microscopes, comparison microscopes, micro-spectrometer with optics, reflective index system, info red micro spectroscope, gas chromatograph/ mass spectrometer, and pyrolysis gas chromatograph to find answers to complex crimes these instrument make it easier to be exact when using proper test procedures.
Collecting trace evidence that is useful for the case has advantages that will later prove or disprove the suspect guilty. Trace evidence in conjunction with witnesses, victims and the suspects testimonies will prove if the criminal is the actual suspect that is in custody. Other analysis such as DNA, finger print, and weapons ballistics will all point to one single source making an undoubtable case against the suspect.
References:
New York State Police (2008) Trace Evidence Lab from source
The Reasons Why Trace Evidence Is Important
Trace Evidence is very important because it solves crimes. If you can identify a series of events that lead to the main outcome you can then solve the crime. Trace evidence may not be enough to prosecute a person but with gathered evidence and time frames you can possibly finger the suspect.
Let’s say for instance a person decides to rob a bank in Manhattan New York. They drive up in an old beat up 1991 Chevy Lumina Sky blue station wagon. Then the first guy gets out, he has a Freddy Cougar mask on and runs in the bank with only a pillow case, a black 9 mm hand gun, large shads and black clothing . He goes in with the other four waiting at the vehicle outside and gets the money from the first checker next to the door, the alarm goes off the robber gets trapped the others waiting outside pull their vehicle through the front door glass backwards the robber runs and gets in the vehicle and takes off. The police get there and find that the criminal that got stuck left his mask and his left shoe at the crime scene.
Here you have a series of events that you could possibly find evidence.
1st piece of evidence are the parts from the vehicle that were left behind
2nd piece of evidence are the motion cameras
3rd piece of evidence is the Freddy Cougar mask
4th piece of evidence is the left shoe you could DNA from the shoe, size of shoe
My point is that with the given trace evidence you may be able to find the suspect.
Physical Evidence
Physical Evidence is a delicate area in law enforcement because you must display the evidence and its relevance to the crime situation. Relevant evidence is explained as having any tendency to make existence of any fact that is related to the determination of the Prosecution or Defense that is relevant to the jury or judge that may affect the outcome of a trail.FRE 403 states that even relevant evidence can be excluded if it is unduly prejudicial, confuses the issue, misleads the jury, or is a waste of the court’s time. Prima Facie evidence, evidence that stands alone , unexplained or uncontradicted, is sufficient to establish a given fact or group of facts.
The following are ways evidence can become corrupt or be verified…
Identification of Evidence
Exclusive Control
Chain of Custody
Storage of Evidence
Delivering Physical Evidence
Miranda
Anyone who is put into custody is entitled to have their Miranda warnings read to them. These 15th and 14th amendments to the constitution forward you your rights to be read in a manner that you can understand. Reading rights are part of a person’s due process of law with being read your rights you are not able to be interrogated or questioned.
The Miranda warning should be read before an arrest or questioning of a suspect.
1. You have the right to remain silent
2. Anything you say can and will be used against you in the court of law.
3. You have the right to talk to a lawyer and have him present with you while you are being questioned
4. If you cannot afford to hire a lawyer one will be appointed to represent you before any questioning if you wish
5. You can decide at any time to exercise these rights and not answer any questions or make any statement
Waiver of Rights
Do you understand each of these rights I have explained to you? Having these rights in mind do you wish to talk to us now?
Exclusionary Rule
Exceptions to the exclusionary rule are used when illegal objects are found in plain view at an airport, during an arrest or when there is no time to obtain a warrant.
The exclusion rule steams from the Fifth and Fourth Amendments that disallows use of any evidence obtained illegally to be used in court.
Illegal search and seizure and objects obtained by such searches are not admissible in the court of law. The fact that the objects obtained add value to the case doesn’t outweigh the fact that the prosecution obtained the property illegally. Violation of any constitutional rights is prohibited in the court of law; the plain sight exception to the exclusionary rule allows contraband to be confiscated when in the sight of a Police Officer.
Search and Seizure
Search and seizure is very important to the Police and Law Enforcement agencies because it is the only way they can gather information and evidence to present to court during prosecution of the court case. It is of utmost importance that the Fourth Amendment rules are not violated such rules of search and seizure entitles an owner their legal right to privacy. The Police must have either a motive, reasonable doubt, or other evidence that leads them to get a search and seizure warrant from a judge; without reasonable cause Law Enforcement is unable to conduct such searches.
The six exceptions to a warrant are as follows…
1. Search and seizure incident to lawful arrest;
2. Vehicle search
3. Inventory searches
4. Consent searches;
5. Exigent circumstances searches
6. Plain view searches
The exceptions to warrants were made to make the Police Officers job safer. Collecting evidence while on the scene, if it is in plain view and cataloging any evidence in the vehicle and or on the person makes it easier to confiscate possible weapons keeping the Police Officers safe.
References:
Criminal Evidence Fifth Edition Norman M. Garland McGraw Hill
Encyclopedia Britannica
http://legal-dictionary.thefreedictionary.com/Exclusionary+Rule
Organic and Inorganic Matter
When selecting an analytical technique you the Forensic Scientist must look at all aspects of the item that tare to be analyzed. Such questions to ask your self are is this organic or inorganic? Is the item qualitative or quantative? Is the item a solid or liquid?
When selecting analytical techniques one must first resolve the question is the object or substance organic or inorganic?
An organic object is a substance that contains carbon and often small amounts of hydrogen, oxygen, nitrogen, chlorine, phosphorus, plus other elements. Inorganic is a chemical compounds are not based on carbon.
Next is to determine whether the object or substance is qualitative or quantative this determination of facts that lead to a sample product of identification of the substance that you as a Forensic Scientist are looking for. Qualitative objects are made up of one single element. Quantative objects or substances are made up of many different molecules and elements combined. When dealing with quantative items the Forensic Scientist must use a technique that will single out the breakdown of the elements and molecules in order to extract exact items to be examined by the Forensic Scientist.
There are many techniques that can be used to analyze materials, substances, and liquids some of which include Chromatography, Spectrophotometer, X-ray and microscopy.
Chromatography is used for substances that contain multicomponent specimens that need to be purified.
Gas Chromatography (GC)
Gas Chromatography or GC identifies illicit substances by using stationary liquid to produce gas that rises into the surrounding environment. The sample is injected into a heated chamber, a constant stream of nitrogen gas flows through the injector forcing the sample through a series of seven columns that has a thin film of liquid present. The columns separate the gases and then the gases enter the detector that activates the recorder producing a recording that traces peaks and valleys based on a timed scale that identifies the concentration of drugs.
Burned Objects Using Pyrolysis Gas Chromatogram
It is a good idea to collect any evidence that you can possibly get when dealing with objects that have been burned. Using the Pyrolysis Gas Chromatogram will help identify the type of material that you have on the crime scene. The Pyrolysis Gas Chromatogram becomes a great use when dealing with paints especially during automobile accidents where the automobile has caught on fire.
Thin Layer Chromatography (TLC)
A gel coated plate is spotted with a droplet of a substance sample from a suspect. Then the plate is placed into a closed chamber that is filled with a rising solvent. The greater the affinity of the substance the greater the speed it will travel up the plat. Then the plate is analyzed and compared with other plates that have been tested with substances similar to the one that has been tested.
Electrophoresis
Electrophoresis separates substances by their migration rates on a stationary solid phase. This Process involves a gel coated plate when under the influence of electric the substance is migrated across the plat due to variances in the size the sample moves across the plat at different variables of speed.
Spectrophotometer
This process uses variants of light to measure the absorption rate of light energy by a substance. The Visible light is light ranging from red to violet. Wavelengths are the distance between crests and adjacent waves. Frequency represents the number of waves that pass through a measured point per second. The first part of the spectrophotometer is the Radiation Source then you have the Monochromator it is a device made for isolating individual wavelengths or frequencies of light; it consists of a prison and a slit. The next piece of the device is a sample holder this holds the substance that is being analyzed by the light source. The detector is the second to last part it converts electromagnetic radiation into signal. Last the Recorder produces a record of the signal.
X-ray
X-ray is used for crystalline materials such as solids with organized atoms. A forensic Investigator may watch the way X-ray diffraction interacts with a substance and record the results. The process of X-ray Diffraction involves analyzing the way X-Rays refract off of the crystalline substances. During the process of using the X-ray it will pass through crystals leaving dark bands called diffraction patterns these diffraction patterns allow the analysis to fingerprint compounds.
The Microscope helps with analysis of many items. Identifying evidence and trace evidence with a microscope is important to making a good case against a suspect. Microscopes have a large range of visible and virtual imaging that identify, compare, and analyze objects, elements, substances, liquids and fluids. The five main micro scopes are the Compound Microscope, Comparison Microscope, Stereoscopic Microscope, Polarizing Microscope, and the Micro spectrophotometer.
The Compound Microscope consists of ten parts base, arm, stage, body tube, coarse adjustment, illuminator condenser, objective lens, and eyepiece. The compound microscope illuminates the subject matter by allowing light to pass through optical lenses to form an image on the retina of the individual’s eye. The magnification of the subject is the total magnifying power of the objective and the eyepiece lenses.
The Comparison Microscope allows for a side by side display that provides the user the ability to analyze both subjects making a comparison of the similarities and differences of the subject being magnified. It uses the bridge that has mirrors and lenses that join two independent object lenses together for analysis of two specimens through the same eyepiece.
The Stereoscopic Microscope is the most frequently used microscope with magnifying power of up to 125x having the capability to show a specimen in third dimension also being able to view a subject at many different angles and a variety of image manipulators that allow the technician to look at the stereoscopic microscope from many views.
A Stereoscopic Microscope can have a polarized lens installed as an accessory along with an analyzer to make the Stereoscopic Microscope into a Polarized Microscope. The polarized Microscope allows the technician to view the subject with a wide array of colors that distinguish the subject and makes easier to identify. The basic use of a Polarized Microscope is to observe minerals found in soil.
The Micro spectrophotometer is a machine that links a Spectrophotometer to a microscope it has a high magnification that is capable of fining very tiny minute pieces of evidence.
The Scanning Electron Microscope SEM emits an electron ray that is has produced by warm tungsten. The Scanning Electron Microscope is one of the highest magnifications up to one hundred thousand it scans three hundred times better than any optical microscope. The Scanning Electron Microscope can further analyze objects by using an X-ray coupled with the SEM Microscope.
When choosing a technique for analyzing elements, liquids, and substances you must weigh all of your options and find the one that suits your needs as the Forensic Investigator. Using the correct process can make a large difference in what your outcome is. Make a plan, document the steps you took to come to your conclusion, photograph your evidence, and document your conclusion.
Collecting Knife Evidence
Get search warrant to obtain evidence. Search warrants are a very important part of confiscating evidence that may be vital to your investigation.Photograph the evidence in its place on the crime scene. Make sure that all photographs are easy to see and have a clear setting. Most evidence photographer’s use 50mm zoom in order to picture the knife in its actual size.Spray the scene with luminal to find all blood.Look for any outstanding blood on the crime scene and perform a percilin test to make sure it is all human blood.Once the fact that the blood is human has been established then precede to collect up evidence weapons, shoe prints ,finger prints, check doors and windows for forced entry, look for half eaten food, confiscate the trash, sweep the room, check the sink, toilet, and all bath rooms for DNA look over blood splatter patterns.Let the knife blood dry and then store it in a box properly labeled with chain of custody and then place a refrigerator until further test need to be preformed. Send all evidence collected to the test lab and all photographs and video to police holding cage with chain of custody intact and a brief description of the items and where they were found.
Blood Evidence
The types of blood forensics are blood spatter, blood stain, puddle blood, drawn blood, blood located on a tool, weapon, knife, or gun.Where you can find blood specimens? You can find blood specimens almost anywhere that the crime scene permits. Most stabbed victims leave puddle blood on the floor or ground. Stabbed wounds leave slit like blood stains on clothing if not cut too deep. Gun shoot wounded people usually have blood stained clothes that a victim may have been wearing at the time they were shot or wounded with blood spatter located on items behind the victim if they have an enter exit wound. Some of the gunshot victim wound types are entrance wound, graze, or an entrance exit wound. The type of wound the victim has allows the CSI agent to analyze how the suspect was standing when they committed their criminal act.
The texture of the blood spatter is important, it allow you to interpret blood stain patterns by observing the direction and thickness of the blood located on the surface. The spatter allows a forensics expert the ability to judge how hard of a blow or strike the subject took before injury or death. It is also possible to measure the direction the suspect moved the striking object before impact. When collecting blood evidence first let blood dry, then place the dried blood stained object inside of a paper bag or box considering how large the object is. If the object is too large then collect samples by scrapping dry blood on to another object, piece of cardboard, or paper then placing it inside of an envelope. Label all forensics evidence properly before sending it to the lab. Keep blood evidence in a cooler or freezer; never leave it in the sun or heat. Proper attire must be worn before starting the forensics operation of collecting blood. Some items that need to be worn for safety purposes are goggle, lab coat, latex gloves, face shield, sleeve protectors, and shoe covers. These clothing items will keep you and the blood sample from being contamination.
References:
Criminalistics An Introduction to Forensic Science Ninth Edition, Author: Richard Saferstein Publisher Pearson Prentice Hall, Copyright 2007
http://www.crime-scene-investigator.net/collect.html
Concerns When Collecting Dried Blood Evidence
Some of the concerns and precautions that should be taken when examining dried blood involve safety, procedure, Chain of command, and Lab analysis. When collecting samples of blood they can be located in splatters, pools, spots, in clothing on a victim or an object. Blood that is in liquid pools need to be photographed and picked up on gauze or a sterilized clean cotton cloth and allowed to air dry. After air drying then the gauze should be refrigerated and sent immediately to the lab for research. Keep all blood items away from heat and the sun’s rays. All clothing items should be placed in a paper bag or box signed with chain of custody and sealed. Make sure not to mix dried blood items are not mixed.
The blood stain pattern is the placing of blood stains at the crime scene. These stains tell a story of what occurred and how the victim ended up in the place where they were found. Investigation of blood can change the suspect of a crime. Forensic investigation of blood can be divided into biological, serology and physics, blood splatter. All fluids in the body are traceable to DNA. Blood components consist of hemoglobin and plasma.
Investigative blood test include the Benzidine color test that has been replaced by the Kastle-Meyer test using a solution of phenolphthalein that changes to pink when small traces of blood are found. To find if the blood derives from an animal or a human the precipition test is used to determine proteins and antibodies in the blood that will allow you to decipher the difference between human trace blood and animal trace blood.
To find hidden blood you might want to use the Luminal test this test allows you to spray a solution on the items or area that you think blood would be present and will display it in the dark with a blue light. All crime scenes that involve blood need to have safety precautions and procedures established by the head CSI agent or Head of Police Investigators.
References:
http://www.crime-scene-investigator.net/collect.html
http://www.officer.com/article/article.jsp?id=35062&siteSection=18
www.washburn.edu/wu-csi/Summer 06 reports/Wilson.doc
Collecting DNA Evidence
In most cases when using hair for DNA the Forensic Investigator wants the hair to be pulled from the root. The actual shaft is not of any use when performing a DNA test, although if you do not find a root for a suspect but a hair shaft a comparison can be performed with a microscope.
Steck-Flynn Katherine (Sunday, 20 September 2009) Trace Evidence Hair from source
Foot Print Evidence
Foot print evidence is vital to Criminal Investigators because they allow inspectors to evaluate if a suspect was at the crime scene or not. Foot prints identify the shoes worn at the crime scene and links them to the suspect or victim.
Foot size, the type of shoe, shoe tread pattern, shoe fibers, all have to be analyzed by the forensics lab for unique details and identification to the subject’s foot size and shoe ware. The walking pattern concerning the stride length of the suspect can identify the height of the person accused of the crime.
The method for identifying shoe prints is to always take photographs of the shoe print first; this protects the evidence from being corrupted. Next you must lift the shoe print using one of the following techniques.
Ways to Lift Shoe Prints
Electrostatic Lifting - mostly used for dust prints on polymer, ceramic and wooden flooring
Card board using a chemical or dye kit enhancer - used for blood prints usually on smooth flat nonporous surfaces
Cast or cutout of the original foot print - used on soft mud
When evaluating shoe prints a Forensic Investigator must analyze sole or heal indents, cuts in the tread and other signs of shoe ware.
References:
http://www.legalmatch.com/law-library/article/footprints-as-evidence.html
Identifying Handwriting
Handwriting exemplars should be similar to the original document as possible. The evidential paper is to be the same as the paper the suspect exemplar is written on. The writing line should pertain to the same script meaning it must match up letter for letter and line for line of writing that the original document produced. The age of the genuine document is typically within two to three years of the exemplar writing comparison.
Exemplar Writing
1. The writer is to be as comfortable as possible
2. The suspect should not be shown the questioned document
3. Suspect should be provided a similar pin and paper to the questioned document
4. The exemplar writing should be the same as the questioned document
5. The suspect should write three times
6. Signatures are obtained by continuous signing on applied documentation
7. A professional document examiner should review the questioned documents
Handwriting Comparison
Dissimilarities between two documents mean that there are two different writers because similarities exist between two writers the possibility of the documents original writer having the same characteristics as the exemplar writing can be common, you cannot take one or two common characteristics to make a positive identification of suspect writing. The writing must contain several characteristics of the questioned document. Looking for characteristics of forged signatures and comparing writing is a hard task. Some inerrancies to look for are loops, curves and circles within the handwriting that display a specific pattern. Other patterns are hand pressure, ink blotting and special characters or zig zag lines. Document examiners must be able to determine habits in writing situations and reconstruct the exact writing habit by producing a similar environment. Under circumstances that are out of the examiners control a writer may not be able to produce the same writing style and habits. Such circumstance of not reproducing the same handwriting would be if the suspected writer was drunk, high, or on medications they may not be capable of producing the same handwriting style and habits.
The ink can also analyzed for its origin by the use of a microspectrophotometer this magnifier uses lenses to identify the chemical makeup of the ink type. Another way to find out if the ink writing was from the same pen source would be to use a thin – layer chromatography the dyes the ink has been produced by are separated and then compared. The United States Secret Service and the Internal Revenue Service maintain the United States International Ink Library which holds more than 85,000 different inks that can be studied and compared for composition.
References
http://www.forensic-documents.com/
Criminalistics (An Introduction To Forensic Science) Ninth Edition Richard Saferstein, PH.D. Publisher: Pearson Prentice Hill Copy right 2007
Evidence Recovery
There are many different types of evidence. Evidence recovery is one of the most delicate jobs a CSI agent can do. Some of the evidence that can be recovered from the body is fingerprints, DNA, semen, teeth impressions, blood, retinal identification, drivers license, home address, mobile phone, wallet, credit cards, vehicle keys, shoe size, and gloves if present.
When recovering evidence you must wear the proper attire for the situation you as a CSI agent have to deal with. Dealing with cases with liquid based materials the CSI team must protect themselves from physical and biological hazards such as explosive dangers, liquid contamination, blood born diseases, air born contamination, skin contamination, and all other factors of biological and chemical contaminants.
The gear that is most often worn by CSI agents are latex gloves, goggles, shoe covers, mouth cover, face shield, lab coat, and sleeve covers.
When recovering blood evidence located on clothing material after it has dried completely the evidence should be placed in brown paper bags or boxes. Keep all blood stained evidence away from heat.
Some of the steps for blood stained evidence:
1.
Air dry
2.
Package in paper
3.
Freeze
References:
http://www.crime-scene-investigator.net/collect.html
http://www.maine.gov/ifw/warden_service/ert.html
http://www.cherokeevillage.org/pd_csi.htm
Hair Good Source Of Evidence
Hair is a good source of evidence it can be identified and lead an investigator to the suspect or identify a suspect. The main parts of hair are the Cortex, Medulla and Root. The cortex which is the protective layer of the cuticle it provides good evidence such as color, shape, and distribution of hairs. The Medulla is a collection of cells that run through the middle of the hair, it tells the forensic investigator if the hair are continuous, Interrupted, or fragmented the medulla identifies individual characteristics about hair shape. The root contains DNA and follicle information that is important to analyzing the hair. The three stages of hair growth are the anagen, cartage, and telogen. The Anagen is the initial growth of the hair that the follicle shows or active growth. The Cartage is an in-between phase that shows some growth and dilution of the hair follicle. The final phase is the Telogen phase it is when the hair is depleted and falls out. When the hair is pulled from the root it leaves a hair follicle that can be identified by DNA testing.
References:
Safferstein Richard (2007) Criminalistics An Introduction To Forensic Science,Tenth Edition
Gun Shoot Residue
Gun shoot residue is different depending on the gun and ammunition that was fired. The mixtures of lead styphnate, barium, nitrate, and antimony sulfide are in different quantities subjected to the type of gun and ammunition manufacturer.
Foot Prints and Walking Patterns
The walking pattern of a person can tell you many things as an investigator. Anatomical structures of a person persuade them to walk different ways. A CSI worker can tell the velocity and direction the suspect was heading. Other important information that can be obtained from the walking pattern are cadence of steps, stride length, base support, step length, foot angle, toe drag and asymmetry. This also can allow an CSI agent to know if the suspect is still in the area a fresh set of footprints can possibly lead you directly to the suspect especially if they have been injured.
References:
http://physther.org/cgi/reprint/60/9/1163.pdf
Establishing Time Of Death
When estimating time of death many factors take place such as questioning suspects and witnesses of the last time they have seen the victim, who were they with, where did they see them, and if the victim presented any problems. Some of the more reliable information about the time of death are body temperature, rigor mortis, lividity and decomposition of the body. Changes in eyes can tell you whether a person has been dead for a long while or looking at whether the eye lid is open or closed, temperature, humidity and air current could possibly be factors that help with estimating time of death. The body temperature can tell allot about immediate death the average temperature 37.5oC at death the body losses heat by 1.5oC until the dead body is room temperature. Insects may tell of the reagent and how long a body has been dead. One insect in particular that is select by region is the fly they lay eggs on the decomposing body and are born within days. Other indications are watches after a strike the watch may break and stop ticking, suggesting the round about time the victim was killed.
An Autopsy may reveal many facts about the time of death and the cause of death. By looking closely at the postmortem lividity of the victim you can tell if lower abdomen and groin area have discoloration or swelling areas to pay special attention to are the penis, scrotum, breasts, and loose attachments of skin.
Fisher Barry A.J. (2004) CRC Press Techniques of Crime Scene Investigation Seventh Edition
© ExploreForensics(2010) Estimating The Time of Death from http://www.exploreforensics.co.uk/estimating-the-time-of-death.html
Visible, Plastic, Latent Prints
Patent prints are fingerprints that are visible to the eye, a simple camera is able to photograph patent prints. Without use of chemicals, magnesium powders or ultraviolet lights patent prints are identifiable by eye They are mostly found in blood, ink, oil or on smooth clean surfaces that display irregularities, door frames or even paper, off white contents that are smooth.
An example of a visible print is a blood stain on the counter of a store that has a finger print imbedded inside it. Impressed or plastic prints are finger prints that are found pressured into objects such as mud, and soft materials placed by finger or hand. These types of prints can be preserved by using ceramic material or by photograph.
Example a person pressed their finger into a wall that was freshly painted and not dry yet leaving an impressed print. Latent prints are prints that have perversely been left; they are created by the perspiration of sweat glands. Latent prints are usually based by oily substances that have been ingested by the person who has left the print behind; a film is identifiable when the finger has come into contact with other substances such as dirt that has been excreted by the sweat glands.
These particles are multiplied when you come in contact with other body parts or skin. Using visual aids such as ultraviolet light and dusting with off colored powders make the latent print visible to the necked eye. Example of a latent print is a print on a car door handle that was left by a suspect.
References:
http://www.exploreforensics.co.uk/latent-prints.html
http://www.dps.alaska.gov/CrimeLab/services/latentprints.aspx
Bullet Shoot Thru Glass
I think it is hard to figure out whether a bullet or other projectile went through a glass because glass is fragile it will not display the exact shape of the object that collides with the glass. If the object enters the glass at an angle it will then make a smaller entrance hole and a larger exit hole. Other factors that make identifying projectiles that has gone through glass hard to determine have to deal with the speed of the object. The speed of the object could be too slow to penetrate the glass without cracking or splintering the glass to pass through or the projectile could have been moving too fast and only bounced off of the glass leaving a larger entrance indentation and no exit hole.
It helps the crime scene investigator to find the object that made the hole in the glass. The variance in size can also be subjected to the velocity of the object that has had an entrance exit through the glass. For the most part shattered glass tells no story about what made it break it only gives the investigator a rough idea of what it looked like before it was broken. Finding possible evidence to support your theory of what broke the glass may help later in trial.
References:
Saferstein, Richard (2007) Criminalistics An Introduction To Forensic Science Ninth Edition
Taking Finger Prints Of The Deceased
Finger printing the deceased involves many different processes that are unique to the crime scene. The involvement of the Crime Scene Investigator will allow for much easier access to the deceased body. There are many kinds of chemicals that a print investigator is able to use. It is suggested that the investigator uses the ink based finger printing technique. If the ink printing technique does not show the deceased prints then they may have to explore using digital photocopy.
Some of the issue and problems that a Forensic Print Investigator may come across while taking finger prints of the deceased are in the state of rigor, mummified fingers make it hard to identify prints, animals have ravaged the caucus, body was found with decomposing fingers that are not in readable state, body found in water way enlarged ridged areas make an unjustifiable print.
First by straighten the fingers then apply black finger print powder with a camel hair brush, using scotch tape and white finger print cards or clear acetate cards, this will provide most finger prints for deceased victims.
If the body is stiffened then you might want to consider using finger strengtheners to straighten the fingers. A horizontal ink roller will allow an easier way to roll the digits of the fingers, and then place them on a piece of ten pin finger print paper. The FBI uses finger printing spoons that work just as well as the finger strengtheners. At times the fingers are too badly twisted in this case you will need to cut the finger at the knuckle joint as an investigator you will have to use bone snips. Other times the tissue on the finger is too tense or weakened a tissue building kit is then needed.
When using a scanned copy print such as live scan you might want to consider the fact that photo images do not come in as clear as the ones produced by using a finger print card. There are many new technologies that provide a scanned finger print that are able to be accessible to you through a PDA device, even though this process is quicker it also has down falls and advances.
One of the down falls is that a scanner will not always scan the print properly. The good thing about using a scanner to get a finger print is that in the case of a finger print that is decomposing the scanned print can be edited to the size that you can identify the finger print.
References:
The hardest prints to obtain are those of rigor and bodies that have begun to decompose. These two types of problem prints make the job of the print examiner harder than normal. Using skin builder injections to inflate skin or to dry skin is one way to get better prints from the deceased. Another way is to use lotions that allow for better skin composition. All in all DNA analysis from teeth and back bone happen to be a more reliable source of identification.
References:
http://www.securityandsafetysupply.com/news/news36.htm
Collecting Evidence For Drugs And Narcotics
Before seizure of any drug related items always process a search warrant, this keeps you in the legal boundaries of search and seizure rules. Make sure to process a chain of possession worksheet making sure that all Investigative personnel are accounted for before touching any items on the crime scene. All items confiscated have to be properly marked with description, amount, time and place for later reference. Items
need to be analyzed by a certified laboratory technician and stored appropriately. SWGDE and SWGIT(Scientific Working Groups on Digital Evidence and Imaging Technology) regulations must be followed providing legal security to the information concealed from computers and other data products.
Scales and proper labels should be used for photographing the crime scene this allows the evidence viewer to know the size of the item that is photographed. Capsules are to be divided into 100 and measured by millimeters; liquids should be measured by liters or milliliters.
When searching for narcotics clothing, cigarette cases, small cases, shoes, wallets hollowed cans, and luggage can all conceal drug items. Suspects can swallow or keep drugs in body cavities, they must be searched thoroughly. Vehicles may contain drug substances in compartments located under the seats in the dash board and in the trunk. When processing drug items make sure to store them in dry containers, boxes and paper bags this will keep the narcotics from becoming contaminated. Liquids should be labeled and placed in a tightly sealed container.
References:
Examples Of Porous Items
An example of a porous item is a newspaper with prints embedded in it. To process such items an inspector must use visual examination, photography, Super Glue Fuming or Crystal Violet Staining, Chemical Dye Staining Luminescent Chemicals or a Modified Physical Developer, Laser or Alternate light Excitation and a photograph of the finished examination.
Photographs provide a good start to any case work it preserves all details. In the incident that you have a lab mishap your evidence will be documented and photographed.
There are several factors to look into before developing latent prints on the newspaper; the first one being is the newspaper wet or dry? If the news paper is wet you would have to allow it to dry at room temperature. This may complicate your investigation procedures simply because it takes time to dry such items. Another factor to ask your self is if the newspaper is glossy or not? If the newspaper is glossy then you would be able to perform Super Glue Fuming otherwise if you have a typical newspaper that is grayish in content with black writing this means that Super Glue fuming is out of the question. If you can’t use Super Glue Fuming then the next option is to use Ninhydrin Developer to produce latent fingerprints.
Ninhydrin developer
It is advised to either spray, dip, or swab Ninhydrin let prints develop at room temperature in the dark. This process may take days for the prints to develop but it is well worth the wait.
Ninhydrin Solution
Ninhydrin 6g
Glacial Acetic Acid 10g
Methanol 20g
Note Stir the above till dissolved then add:
Genesolv 2020 100mL
Zinc Chloride Solution
Zinc Chloride 6g
Glacial acetic Acid 10mL
Ethanol 50mL
Propanol 10mL
Note : Stir the above until completely dissolved, then add
Genesolv 2020 200mL
References:
Advances in Fingerprint Technology Second Edition Edited by: Henry C. Lee and R.E. Gaensslen Published by: CRC press Copyright: 2001
Fingerprinting Drowned Victim
First let the corps dry before trying to take any finger prints.
Next use finger straightener to straighten out the fingers
Third finger spoons to keep the finger while taking the finger prints
Fourth use a roller to roll ink into the fingers that are to be finger printed
Fifth move the finger on a finger print card starting from right to left
Sixth the skin is too soft use a tissue building kit
