How to Become a CSI
The Corpse as a Scene
The Corpse as a Scene
Miami-Dade Police Department
The corpse at the scene of a brutal homicide can often tell those investigating the death many things. The forensic evidence left behind on the corpse, often times becomes the silent witness against those who commit the most heinous of crimes.
Each investigative entity in a homicide investigation has an assigned duty in the investigation. The crime scene investigator or evidence recovery technician is a support entity in an investigative process. Their assigned task as a forensic specialist deals with the physical evidence.
Their task will include recognizing the items of evidence, documenting any and all evidence encountered, establishing a chain of custody with the items of evidence by isolating and collecting the items, securing the evidence by packaging each individual item in a way that it is not contaminated or lost during the transporting and routing of the items to the laboratory. The items of evidence are distributed to the particular forensic disciplines of the laboratory for analysis.
The success of any investigation starts with a good working relationship between all parties that will be involved. This will require cooperation, commitment, and communications between the detectives, crime scene, medical examiner, and laboratory personnel.
We have always enjoyed a strong working relationship with each of the individual entities. There is a knowledge and respect between each of the entities for their duties to the investigation.
How we got started
In 1994 two sets of unrelated serial murders necessitated a close look at a number of protocols to be fine tuned in establishing how we would examine the corpse in our search for forensic evidence to those crimes. During all crime scene investigations involving a sudden unnatural death the body, being a part of the crime scene, is examined for the possibilities of evidence.
A Task Force
Several of our units were selected to become members of a team that would process the crime scenes believed to be related to the serial homicides. The purpose of the teams were to keep the awareness and consistency in the overall investigations at a maximum. My assignment quickly became to focus my efforts and attention to the examination and processing of the deceased.
Being assigned to work all of the serial crime scenes, my first decision was that the corpse would be treated as an individual scene in and of itself. This would require an intensive examination of the body. The examination would be for the obvious types of evidence that might be found on any other established crime scene.
Evaluation of a Crime Scene
In crime scene investigations the scene is secured by establishing perimeters. An initial walk through of the scene is done for the purpose of examining the scene for potential evidence.
Types of Evidence
The initial examination of the body was to detect any (trace evidence) foreign hairs, fibers, or body (biological) fluids that might be present. The examination was also a preliminary search for any trauma or noticeable wounds. If an item was observed then it would be documented with a series of photographs.
In the forensic field the accepted methods in trace evidence collection is either with vacuum, trace lifter, tape, tweezers, or in a clean sterile tissue. When the scene is a small area, such as a deceased person, the suggested methods for collecting an observed item such as a single strain of hair or a fiber would be with a pair of tweezers and or a clean tissue.
If the tweezers method is chosen care and practice is essential. When you add factors like wind and environment into the equation, it is very easy to lift a small hair or fiber from an object and find it missing when you raise it to an envelope.
A suggestion would be to hold a tissue in one hand close to the area of the trace item. Lift the item with the tweezers in the second hand. Place the item in the tissue with the tweezers. Then fold the tissue and place the folded tissue in an envelope or pill box.
An easier method would be to just take the tissue and pinch the hair or fiber into the tissue. Fold the tissue and put it into an envelope or small pill box.
In learning to use all available resources save the empty plastic film canisters from your 35mm film package. The canister can be used as a packaging medium. The tissue securing the trace item can be folded and placed into the canister.
Any biological fluids can be collected by scraping or swabbing techniques. If the fluid is on an item of clothing, then the item of clothing can be collected.
Biological fluids can also be collected by using tape applied over a dried stain. Make sure to check with your laboratory to see if this is an acceptable method for their standards. The use of tape as a collection technique for dried biological stains is an acceptable method of recovery in the forensic field, although some laboratories discourage its use. After lifting a taped stain it would be placed on a latent fingerprint backing card.
Identification has always been one of the main goals in criminal investigation. This is accomplished through fingerprints recovered form various surfaces at the crime scene.
Recovering latent prints from human skin is not a difficult task. Just like in all latent print recovery the investigator has to have the knowledge of the surface, the methods used to recover latent prints from certain surfaces and the conditions and factors for depositing, developing and recovering the latent print.
Usually in latent print recovery the investigator is accustomed to dealing with porous or non-porous surfaces.
The skin has traits and characteristics of both porous and non-porous substrates. It is also elastic in that it moves, stretches, and then returns. Then there is the shedding of old cells and regenerating of new cells. The skin also releases perspiration and oils. These are the added factors and conditions that have to be understood to be successful in recovering latent prints from human skin.
In the laboratory where you have ideal conditions or a controlled environment is where the investigator needs to gain the experience and confidence to be able to go into the field and attempt the techniques for these processes.
Lets look back
When we started responding to these serial crime scenes, very little study was being done on recovering latent prints from human skin. From the mid 1970's to the mid 1980's There were a half dozen documented cases involving the successful recovery of prints of value in the field.
One of those cases, believed to be the first known documented case, had resulted in the successful prosecution of the subject in Miami-Dade County.
In 1991 an article appeared in the journal of forensic identification documenting the recovery of latent prints on human skin. The article aroused our curiosity and rejuvenated our pioneer spirits as it had done in our predecessor. A series of experiments were done around our office with volunteers using various lifting mediums to transfer latent prints deposited on the inside hairless areas of the arm.
In a modern fingerprint technology class that we conducted for our departments training bureau, a segment was added to our curriculum devoted to testing various lifting mediums for transferring of deposited latents.
Where do we start
This was a total team effort by just about everyone in my unit. The entire group had input and contributed to the methods that we would ultimately apply in the field. We carefully studied the documented cases. We were looking for a common clue to the methods applied in the field that had resulted in success.
We also examined what information we had gotten from our brief studies in the office and in our classes.
The documented cases revealed a variation of three (3) methods used in the developing and recovery process. So we decided to establish a sequence of all three methods. We felt this would allow us more of an opportunity for success. Similar to using a sequence of chemical's to process a porous item.
Direct lifting method
The first method in the series would be a direct lifting method. This method would start with a lifting medium.
A lifting medium would be any item which could be used to press and roll on the surface of the skin to allow a transfer of any impression which might be on the surface of the skin. The areas that were targeted were any exposed areas
We had practiced with many different types of lifting mediums but settled on a kromekote backing cards used to back lifted latent prints.
After the card was removed from the surface it was dusted with magna powder. If ridge detail was developed then latent tape was laid over the ridge detail to protect it from being scratched or wiped away.
The back of the card was filled out. Starting with the location of the body where the transferred lift was obtained and all other information usually documented on a latent lift.
Super glue method
A chamber was constructed and placed over the corpse for fuming. Afterwards the victim was examined for any developed prints.
Using magna powder and an applicator, the powder was applied directly onto the surface of the skin. If a latent print was developed it would be lifted with latent tape.
When is it necessary
A criteria using common sense has to be established for when to use such an extensive examination of the body.
As an example; if you have a death that resulted from a drive by shooting. The victim was shot, and collapsed in his front lawn, by someone in a passing vehicle. It would not make sense to thoroughly examine the body for trace, biological or fingerprint evidence.
An attendant at a business is shot by a robbery subject some 5 feet or more away. This would not require a thorough examination of the body for trace, biological or fingerprint evidence either.
We chose to establish the following as our criteria:
Since 1994 I have processed more than a dozen bodies fitting our selected criteria for using this intensive examination process. Although I have not had the success of recovering any latent print evidence from the corpse, it does not deter me from giving the same aggressive effort each time. My opportunity will come!!
Most of the cases that were responded to have successfully resulted in valuable trace and biological evidence being recovered.
A special thanks to those determined individuals who pioneered the innovate ideas, to those determined colleagues whose tireless efforts will not be forgotten, and those with the dedication to currently dispense these valuable methods and ideas.
Article submitted by the author