CJ 370 Unit 9 Assignment 1

CJ 370-01: Crime Scene Investigation II

Unit 9 Assignment 1

Purdue University Global

Unit 9 Assignment 1

Footprint along with footwear evidence is very important to an investigation. This may be the only evidence that is left at a crime scene, and it could very well lead the detectives to the suspect that committed the crime. It is very important that the evidence be photographed and collected in the proper way. This paper will discuss how to preserve and photograph this type of evidence and how to cast the impressions. It will also discuss the proper way to examination firearm evidence as well.

When the investigator sees footwear impression, he or she should include a landmark in the photograph so that the location of the impression is clear. For example, if the impression is below a window then the window should be photographed as well as the impression. It is necessary to include an evidence marker in the photograph as well. After the investigator takes the photographs of the impression, which needs to include up close photographs as to show the impression better. It is best to use black and white film, because it provides more detail and contrast versus using color film (Bodziak, 2016).

The camera should be placed on a tripod and positioned so that the camera’s film plane is parallel with the impression. This is done to minimize distortion in the photo, the angle finder can measure the angle of the impression and then by putting the angle finder on the camera’s eyepiece, the angle of the camera can then be adjusted to match the angle of the impression. A scale should be placed by the impression, the scale should be an L shape. It is important that many photographs be taken of the impression (Bodziak, 2016).

The equipment for casting an impression would include dental stone and sulfur, zip-lock bags, mixing bowls, water, measuring cups, a spoon or stir stick, a hot plate for melting sulfur. To cast an impression with dental stone in dirt or sand, it is necessary to prepare the impression. If it is a fragile impression, a fixative may have to be used. If this is the case care should be used to lessen the chance of damaging the impression. The average footwear impression will need two pounds of dental stone and ten ounces of water. The amount of water may vary depending on the casting product. This should be mixed constantly for three-to five minutes. Pour the casting material carefully outside the perimeter of the impression and direct the flow into the impression. The cast should be thick enough to avoid breakage. A dental stone impression should be allowed to dry for at least 48-hours, before cleaning it (Fisher, & Fisher, 2012).

The cast has to be totally dry before packaging it. The cast should be properly packaged in order to avoid any breakage. If possible, the cast should eb cleaned in the lab by the examiner. Prior to cleaning the cast, it may be necessary to preserve any soil that is attached to the cast. The excess soil and sand can be cleaned from the cast by using water and a soft brush (Bodziak, 2016). Footwear and footprint is a lot of times overlooked as evidence at a crime scene.

In cases such as homicide, assault, and robbery crimes firearm evidence may be present. There are other crimes where a firearm may be used such as rape, burglary, and drug deals. If a revolver is found at a crime scene. The location has to be diagramed and photographed, and once this is done the investigator has to treat the weapon as being loaded to be on the safe side. The investigator would move the cylinder by two pen or scribe marks on the top of the cylinder along each side of the top strap of the frame. The investigator would be wearing gloves and all cartridges would be removed and they should be handled in a way as to not destroy any fingerprints that may be on them. Each cartridge should be packaged separately and referenced to the information in the field notes, the actual cartridge should not be marked (Saferstein, 2011),

The investigator should then examine the weapon for trace evidence such as hair, tissue, blood, or fibers. The weapon should not be dusted for fingerprints. The investigator should take the weapon to the laboratory and asked that it be processed for fingerprints. The ideal way to transport the weapon is in person if possible. A loaded revolver can be transported in a specially constructed box which has the means of securely holding the weapon and has a metal plate that blocks the muzzle. If the weapon has to be mailed it has to be unloaded and securely packaged. An identification tag should be placed to the trigger guard of the weapon, and should contain the serial number, make and model of the weapon, and the date and time, the case number, and the investigator’s initials on it (Saferstein, 2011).

Firearm evidence can be recovered in a lot of different ways, the weapon itself may be left at the crime scene. The investigator may find bullets, bullet fragments, cartridge cases, or shotshell wadding. Bullet evidence may also be obtained during an autopsy or if the victim is alive and requires surgery, the doctor may retrieve the bullet in the operating room. A bullet may be lodged in the wall, or a door at the crime scene (Saferstein, 2011).

The investigator may have to test for gunshot residue, and this is done by the Griess test. To see if gunshot residue is on a person’s hand the investigator would use adhesive tape to the hand and recover any adhering residue particles. Another way would be to swab the hand with cotton that has been dipped into five percent nitric acid. The scanning electron microscope is another way to detect gunshot residue. This includes applying adhesive on the hand then locating the microscopic primer and gunpowder particles by using the scanning electron microscope (Osterburg, & Ward, 2014).


It is very important that the investigators collect all evidence at a crime scene no matter how small it may seem. Care has to be used when casting impressions of footprints or footwear evidence. Care has to be used when it comes to the examination of firearms, and safety has to be taken into consideration as well. Plenty of photographs of the evidence has to be taken, and the personnel has to wear gloves, and follow the chain of custody so that the evidence does not become contaminated in anyway whatsoever. The steps to collecting evidence have to be followed and there are no room for any mistakes to be made at all. If the evidence should become contaminated then it may destroy an entire case, so one must always follow the rules and if they do make a mistake try to get it corrected at once.


Bodziak, W. J. (2016). Forensic footwear evidence. (1st ed). Boca Raton, FL: CRC Press.

Fisher, B. A. J., & Fisher, D. R. (2012). Techniques of crime scene investigation. (8th ed).

Boca Raton, FL: CRC Press.

Osterburg, J. W., & Ward, R.H. (2014). Criminal investigation: Method for reconstructing the

past. (7th ed). Scotch Plains, NJ: Anderson Publishing.

Saferstein, R. (2011). Criminalistics: An introduction to forensic science. (12th ed). Upper

Saddle River, NJ: Prentice Hall.