Processing a Vehicle for Forensic Evidence
The exact order in which evidence is collected from any vehicle will depend of the circumstances of the crime. In most instances the outside of the vehicle is processed first. However it is possible that in some cases heat or cold sensitive biological evidence may be present which requires immediate removal.
The processing of any vehicle starts with the recovery of the vehicle. The officer who responds to and scene where a vehicle is to be seized should be aware of the possibility of contamination of the scene. Until it can be ascertained what type of crime the vehicle was involved in it is good to assume that all types of evidence are present and need to be preserved.
Just as you would at any crime scene one of the first things to be done is a quick visual search. This simply insures that there are no people in the vehicle. It also insures that there are no dangerous substances or explosives in the vehicle. Wear surgical gloves when examining the vehicle especially if the type of crime it was involved in is unclear. Try not to sit on the seats when looking for ownership information. A vehicle is basically a mini crime scene so "securing the scene" is step one.
Once it has been secured the vehicle can be transport. Instruct the Tow Truck Operator that if he/she has to enter the vehicle that gloves and a mask should be worn. This helps reduce the chance of contamination of the existing evidence. If it appears that soil adhering to the vehicle may be used as evidence the vehicle be transported using a flatdeck tow truck rather than one that uses a dolly system. Large chunks of soil in wheel wells and on the undercarriage can be analyzed to determine where the vehicle has been. These can be dislodged and lost during transport when a dolly system is used. If a flatdeck truck is not available soil samples can be collected before towing.
When the vehicle is ready for towing a police officer should follow the tow truck to the area where is will be processed. This insures continuity of the evidence. The area should be secure and have temperature regulation. In cold climates vehicles must be brought indoors and allowed to dry before fingerprinting can be done. In very warm climates moving the vehicle indoors can help preserve heat sensitive biological evidence such as DNA or entomological evidence. Garages with forced air electrical heaters which blow air downward onto the vehicle are not appropriate. These types of heaters destroy or scatter hair, fiber, paint transfer, soil and other trace evidence.
Probably the most common reason for recovering a vehicle for processing is because it has been identified as stolen. Very often these stolen vehicle turn out to have been used in other crimes such as bank robberies and gang related shootings.
When processing a stolen vehicle the most common types of evidence which are collected are fingerprints and photographs. However, it may turn out that the vehicle is associated with more serious crimes. If you do not plan to collect evidence other than fingerprints try to leave the interior untouched in the event that other trace evidence becomes important later.
The first thing which should be done is to record the license number and serial number of the vehicle. This can be done in the form of notes or using photographs. Ideally both methods should be used. Photographs of the vehicle from a distance from several angles can be taken for the purpose of identification. Close ups of any damage to the vehicle should also be taken.
Place a card with the investigators/photographer's name and regimental/identification in the windshield next to the serial number and photograph it. This identifies the vehicle and who processed it.
Once the vehicle has been photographed the outside of the vehicle can be dusted for fingerprints. The general areas to be dusted are the door handles, top of the door, gas tank cover and widows. The type of powder used for dusting these areas is up to the individual technician but should be of a color which contrasts the color of the vehicle. Once this is done any visible prints should be labeled, photographed and lifted. For example, if there were three fingerprints visible on the driver's door above the door handle correct labeling is done as follows.
1) Circle the print or set of prints with a grease pencil of which the color is in contrast to the vehicle's color.
2) Mark the outside edge of the circle with the number of the print or set of prints. For example if the three prints are the first set you find it is labeled R-1. R is used because it is obvious when the letter R is reversed. This can happen when the prints are lifted and are being view from the wrong side of the print card.
3) After the letter R and the number of the print letters representing the individual fingerprints are added. The label will then read R-1 a,b,c.
4) Apply scale tape to show the size of the fingerprint horizontally underneath each print. It is important to place the scale tape in this way to help reduce photographic distortion of the scale (Bowers, 2004).
5) Within the circle label each print as a, b, or c and so on. Draw an arrow to indicate which way is up.
6) On the outside of the circle add the case number, the date and the technician's identification number or regimental number.
7) Apply fingerprinting powder to the entire circle for contrast and photograph at F32. The depth of field should be as large as possible. The resolution should be 1:1. Remove the flash from the top or side of the camera and let it dangle below the camera to avoid hotspots on the photographs.
The prints can be lifted using smooth surface lifter tape. For rougher surfaces a commercially available product called Gellifters can be used. Gellifters have the drawback of producing a reverse image or the print whereas Tape gives an accurate view because if can be viewed from either side.
Vehicles typically have rough surfaces in the interior which make it difficult to find clear prints. Some rear view mirrors, gear shift mechanisms and seat belt buckles are smooth and can be checked for prints. The surface of the radio or other stereo equipment as well as any compact discs or tapes in the mechanism should be checked for prints. The underside of the panel which covers the ignition can yield usable prints. Thieves will tear off this cover in order to access the ignition mechanism leaving prints behind.
As was mentioned earlier it may turn out that what originally was thought only to be a stolen vehicle is associated with another crime. Alternately the vehicle might be associated with a crime right from the time it is recovered. The general rule is to record and collect evidence as you proceed from the outside to the inside of the vehicle.
If the crime is of a nature in which DNA sample will be of use then collection of certain items may yield a sample. The door handles, seatbelt and buckles can be swabbed. Cigarette butts can be collected in a paper envelope. As a rule biological evidence is best stored in paper to avoid degradation which occurs if the sample is or becomes wet. Wet samples such as blood soaked clothing or upholstery should be air dried before packaging. Do not heat dry biological samples. Drink containers are also a source of DNA.
If the crime associated with the vehicle is sexual in nature any stains on the upholstery should be examined. The upholstery may have to be removed and transported to the laboratory for DNA testing or samples of the stains cut out for further analysis.
Hair and fiber evidence can be collected using a vacuum system or using lifting tape. The tape is used to lift hair and fiber from the interior surfaces of the vehicle. The tape is then transferred to lift cards and labeled as to which part of the vehicle they came. This method would be used in cases of sexual assault, kidnapping/abduction, murder and other crimes where it is necessary to establish the presence of a suspect or a victim inside a vehicle. Hair and fiber may also be recovered from the bumpers, windshields and undercarriage of vehicles involved in hit and runs.
Drug evidence can come in many forms. The best response to this situation is to bag and store items in the same condition that it was found. That is if it is dry store it in paper evidence bags. If it is wet store it in the original container and package around the original container.
Tire tracks and footprints may both be present. When casting tire tracks in mud dental stone will work. Always photograph tire tracks on a 1:1 scale with a ruler or other measuring device visible along the bottom of the photograph. If you are trying to cast tire tracks or footprints in snow a different method should be used. There is a commercially available product which can stabilize snow called Snow Print Wax. Although it seems strange because it is mixed hot the best method seems to be the use of flour sulfur. It is difficult to mix and must be boiled. However, on contact with snow it hardens creating an accurate cast (Genge, 2002)
When processing a vehicle which may be associated with a crime in which tire track impressions where taken measurements of the tread width and comparison prints should be taken. Tread width measurements are taken from the point of one tread line to the one opposite it. Again, always photograph the tread pattern with a measurement instrument in view to show scale (Saferstein, 2004).
Paint may be transferred from one vehicle to another in the case of a hit and run. Paint transfer to or from an object which might have been struck may also occur. Paint flecks can be gently scraped into a plastic or paper envelope. If feasible the entire bumper or other area of the vehicle can be removed and sent to the laboratory. The F.B.I. maintains a record of many of the colors and chemical profiles of vehicle paints. Samples can be submited for analysis. See the F.B.I. website at:
Any paper or questioned documents can be placed in a paper envelope and transferred to the laboratory for fingerprinting and handwriting analysis.
This also applies when dealing with money stain with dye pack dyes. If the money is dry it can be placed in plastic evidence bags.
Whenever any samples are taken exemplar or control samples should be taken. If paint, fiber or other trace evidence is collected a sample from an area not thought to contain evidence should be taken. This helps insure that a substance in the natural paint, fiber or other material inside the vehicle doesn't contain material which might cause a false laboratory result.
Bullets or shell casings may be found inside the vehicle or lodged in the body of the vehicle. Vehicles involved in drive by shootings, gang related activities and robberies commonly have this type of evidence in them.
Ballistics evidence is used for two types of identification. The lands and grooves as well as the direction of twist created when the barrel was manufactured are unique to the various manufacturers. The number of lands and grooves plus the direction of twist will tell an investigator the make and model of the weapon that fired the bullet. This is called "class' evidence because it indicates the type of weapon but not the particular weapon which fired the bullets.
The striations on the bullet are created by minute imperfections inside the barrel. These are considered "individual" characteristics. These tiny markings can be matched to a specific weapon. It is therefore important when dealing with bullets to handle them in a way in which damage to these tiny lines is prevented.
Loose bullets or casings are best collected by hand using latex gloves. Each bullet should be wrapped in protective material and packaged in such a way as to prevent jostling. Plastic vials filled with protective material can be used to store individual bullets.
If the bullets are lodged in the body of the vehicle they may have to be removed using tweezers or forceps. If this becomes necessary use rubber/vinyl coated ones. Use of metal instruments can cause damage to the markings on the bullet destroying the possibility of a match to a suspect's weapon. It may become necessary to use the services of a person skilled in auto body work to assist with the removal of door panels etc. to recover bullets. When interior door panels are being removed place a felt pad below the open door to prevent the bullets from falling to the ground and being damaged.
Bullets can also yield fingerprints especially if a weapon is recovered which still contains unfired rounds. Always package live round separately and label the package clearly as to the contents.
When all the evidence is package it can be transported to the Laboratory which will be further processing the evidence. It is advisable for the investigating officer to consult with the supervisor at the laboratory as to the nature of the crime. If the laboratory personnel know what the investigator is trying to determine he/she can direct the appropriate testing.
Note: I have by no means covered all of the types of evidence found in a vehicle but have tried to touch on the most common. I would like to thank Constable Steve Dueck of the City of Calgary Police Service, Crime Scenes Unit in Calgary, Alberta, Canada for his time and effort in teaching me what they do. Also, thank you to Sgt. Bill Sturgeon who gave me permission to tag along.