Recovering Latent Fingerprints from Cadavers
Written by John Louis Larsen   

IN A HOMICIDE CASE, the recovery of latent impressions from a body is just one more step that should be taken in the process of completing a thorough search. This article is directed at crime-scene technicians and the supervisors who support and direct evidence-recovery operations both in the field and in the controlled settings of the medical examiner’s office or the morgue under the coroner’s direction.

I have patterned my protocol for conducting latent-fingerprint recovery operations on a cadaver using an article by Dale Moreau, Supervisory Special Agent (SSA) of the Federal Bureau of Investigation (FBI) Forensic Science Training Unit at the FBI Academy: “Crime Scene Search as a Process”. This protocol calls for the corpse itself to be looked at as a crime scene within the overall scene. Keeping this in mind, Moreau’s twelve-step approach works well for the overall latent-fingerprint recovery on a body. Here are the steps:

  • Preparation of equipment
  • Approach to the scene
  • Preliminary survey
  • Narrative description
  • Scene photography
  • Scene sketch
  • Evaluation of latent-fingerprint evidence (including DNA)
  • Evaluation of physical evidence
  • Detailed search
  • Collecting, recording, marking, and preserving evidence
  • Final survey of the scene

Release of the scene
Before proceeding further, I should point out that it is incumbent upon the crime-scene technician or investigative personnel responsible for the crime scene to have a good working relationship with the medical examiner or the coroner. The laws in most of the states prohibit crime-scene personnel from handling a corpse unless given specific directions by the medical examiner or coroner. To do otherwise is considered to be a criminal offense punishable by fine and imprisonment.
Once permission has been obtained from the medical examiner or coroner, the following steps need to be taken to lift latent fingerprints from skin:

Step 1:
Preparation
Basic forensic supplies that should be on hand to make a fuming chamber:

  • Twelve 3-ft. lengths of 0.5 in. PVC pipe
  • Four 90° three-hole corner caps of 0.5 in. PVC
  • Three “T” couplets of 0.5 in. PVC
  • Two painters’ plastic cover sheets large enough to cover a single bed
  • Scissors
  • Micro-burst variable hot plate
  • Some small disposable aluminum dishes for the fuming operation
  • Liquid fuming agent (cyanoacrylate, such as Superglue)
  • Roll of blue painters’ tape that is at least 2-in. wide
  • Two 50-ft. heavy-duty electrical extension cords
  • Spray bottle
  • Fluorescent powder
  • Semi-fluorescent powder
  • Black-light lamp
  • One bottle of Kodak Photo-Flo 200 solution

You will also need some equipment to conduct “pressure-transfer lifting”
—a term coined by the author for easy reference. Here is that list:

  • A roll of white adding-machine paper, fine grain, and 2- to 3-in. wide
  • Magnetic black powder
  • Magnetic wand
  • Scissors
  • Extra-fine retractable lead pencil
  • Rifle and gun boxes

Here is the equipment that will be needed for the iodine-fuming method:

  • Iodine Fuming Stix from the Lynn Peavey Company

Since all latent fingerprints should be photographed before they are lifted, the proper camera equipment is also necessary. In all instances, it is recommended that you use a digital SLR camera with a 60-mm micro AF lens and independent flash with off-camera TTL flash extension cord. If possible, use a tripod. Use 3-in. stick-on photo scales in gray, white, and black.

Step 2:
Approach the scene (the body)

Extreme care should be taken when making the initial approach to the body. All physical evidence around the body needs to be photographed, sketched, and collected. Remember: The corpse is a crime scene unto itself. Exposed areas of the body should be carefully noted and thoroughly documented on an independent sketch.

Step 3:
Conduct a preliminary survey

When conducting the preliminary survey of the body, the focus usually falls on the observable areas of trauma. The investigator will need to look beyond the trauma and attempt to keep an open mind in processing the body areas.


Step 4:
Document a narrative description

You should execute a narrative of the scene in written or recorded format.


Step 5:
Photograph the body

The body needs to be photographed from all possible positions, including from above. Any close-up photographs should have photographic scales in place, especially when they involve open areas. Document all photographs using a photographic log.


Steps 6, 7, and 8:
Sketch and evaluate

In Step 6, you should sketch the corpse in its entirety as it is being evaluated. The north directional marker should be included in the sketch. In Step 7, you will evaluate the areas on the body that are most likely to yield latent prints. The areas to be pressure-transfer lifted or processed in some other way should be marked on the sketch. In Step 8, you should continue the process of conducting a visual examination and evaluation of other physical evidence categories, such as DNA or hair and fibers.


Step 9:
Recover the latent prints

The following techniques can be used to recover latent prints from the corpse:

  • Pressure-transfer lifting or other pressure techniques
  • Superglue fuming
  • Skin-print powder processing
  • Iodine fuming

In recovering latent fingerprints from the skin of a cadaver, the author recommends several different procedures. In the photo on the facing page, the target area of the body has been processed with superglue and fingerprint powder is being used with a feather duster. In the two photos on this page, the technician is using the pressure-transfer lifting technique. This involves pressing clean adding-machine tape over the target area to lift the print...and then cutting that section of tape from the roll so it can be properly handled as evidence.

The remainder of this article focuses on each of these techniques used for latent-print recovery on human skin.
The technique used in pressure-transfer lifting
Using a clean spool of adding-machine tape, press and roll the paper—while still on the spool—over the target area.
Cut the used section of paper from the roll. Designate the direction in which the paper was rolled, as well as the area of the body from which it was lifted. The cut section of paper should be handled as evidence.

Process the rolled paper using the magnetic powder. The Chicago FBI Evidence Response Team (ERT) has successfully used basic violet and Ultra-Blue magnetic powders.

If an impression is discovered, protect the impression as you would a shoe print impression by placing and suspending the paper in a protective evidence box.

Environmental and climatic factors such as damage to the victim’s body by the assault of bacteria, insects, and environmental elements supplied by “nature”—such as thunderstorms and snow—can affect the outcome of the process. In their study, Recovery of Latent Fingerprint Evidence from Human Skin: Causation, Isolation and Processing Techniques, William Samp-son and Frank Shonberger contend that the skin needs to be in the range of 70° to 72°F, and the instrument being used to attempt the lifting should be preheated in cold conditions and vice versa if the conditions are hot in an attempt to reach a range of 70° to 80°F.

Throughout the period of 1989 to 2003, the Chicago FBI ERT would attempt to recover latent impressions from bodies when the skin temperatures were between 80º to 86ºF. The team had two successful recovery operations in that time span. One of the successes was the Patricia Scott case.

On April 25, 1996 at approximately 9:30 a.m., the body of Patricia Scott (black female, age 30), was recovered by the Chicago Police from a trash bin behind Calumet High School. The body temperature was between 60º and 70°F. The body was delivered to the Cook County Medical Examiner’s Office (CCMEO) by 10:30 a.m. The detectives assigned to the case asked for directions regarding what to do with the body. They were advised that the body was not to be refrigerated, washed, or disturbed. The medical examiner, Dr. Edmund Donahue, gave permission for Special Agents to conduct the processing for latent impressions with the understanding that Scott’s hands not be debagged or disturbed in any way. At approximately 5:30 p.m., Scott’s body was processed for latent impressions in the Cook County Medical Examiner’s hallway which was maintained around 75°F.

If at all possible, the body should be processed within the first 24 hours and should not be refrigerated. When the body is removed from the refrigerated environment, moisture will develop on the skin and effectively contaminate the process by leaving moisture impressions on the recovery transfer materials.

The pressure-transfer lifting method can be used with other ordinary materials besides paper such as glass plates, metal plates, or photo paper. The most important part of the process is applying even pressure to the target area. If too much pressure is used, the latent impression will result in a compressed dot or smudge.

In the these three photos, the technician is lifting latent fingerprints from human skin using another form of the pressure-transfer lifting technique. In the photo on the left, the adding-machine tape is applied to the target area of the body—in this case, the cadaver’s arm—and is pressed against it to lift the latent fingerprint. The tape is then positioned on a flat surface (center photo) while the print is processed with magnetic powder. The end result is shown in the photo on the right: a latent print that is suitable to use as evidence.

Supergluing
(cyanoacrylate fuming)

Skin is non-porous—thus, it is suitable to use the superglue-fuming process. Processing can be accomplished in open air or by tenting.

Open-air processing uses a fuming wand to generate controlled bursts of the cyanoacrylate vapors. These bursts are no longer than 10 to 15 seconds in duration. Extreme care must be taken not to burn or overexpose the skin to the superglue fumes. Before a technician attempts this process, it is wise to practice fuming on an inanimate object to develop the appropriate distance between the fuming wand and the surface being processed. A small test print on the surface to be processed can take the guesswork out of the procedure. The fuming wand distance should be between 10 and 12 in. below the target area. After fuming, use any one of the ultra-sensitive non-carbon-based powders in an attempt to uncover a possible latent impression.

Tenting allows for the examiner to cover larger areas of the body while maintaining a controlled, safe environment. Tenting can be accomplished using an assortment of paraphernalia. For the purposes of this article, the tenting construction is described as being put together using conventional PVC piping and a painter’s plastic drop-cloth of appropriate size.

Before covering the tent framework, place the micro-burst variable hot plate inside the framework in the area to be fumed. (The micro-burst variable hot plate is manufactured by Barnstead International and is sold by Evident Crime Scene Products.) Then, follow this procedure:

  • Cover the tent and turn on the hot plate to at least Number Six (about 250º to 300ºF) on the heat-setting dial. Give the plate at least one minute to heat up.
  • Place a test fingerprint on the inside of the tent near the target area to be fumed. To make the test print easier to locate, put a circle around the site with an indelible marker.
  • Put a quarter-size droplet of super-glue into an aluminum glue-fuming dish and place the dish on the burner.
  • Watch the test print. When the test print begins to develop, carefully remove the aluminum glue-fuming dish and unplug the burner.
  • Slowly and carefully remove the tenting material, taking care not to breathe the fumes or even put your face over the fuming site. Since the latent impressions on the skin are polymerized, the examiner can safely leave the area until the cyanoacrylate fumes dissipate. The examiner should take safety precautions by wearing eye protection and a mask. If possible, the area should be well ventilated.

Once the fuming process has been completed, the examiner should conduct the standard latent-recovery operations. The examiner can use a variety of different latent-recovery techniques to enhance and bring up latent images. The techniques that can be utilized include traditional contrasting powders and new semi-fluorescent or fluorescent powders. Semi-fluorescent and fluorescent powders should be used with a black light or an alternate light source (ALS).

Documentation of the impressions should be accomplished through photography. Remember to use photographic scales and take multiple shots.

Skin-print
powder processing

Once the target area of the body has been processed with superglue, traditional contrasting fingerprint-powder techniques can be utilized. Since skin is nonporous, the dusting process is done in the traditional manner with a brush or a feather duster.
The author has had only one success with this technique—and that was in a controlled environment on a woman’s forearm in the dry heat of a crime laboratory. The powder used was Skin Print, a new non-lampblack carbon-based powder from Doje’s Forensic Supplies. The old carbon-based lampblack

powder tends to fill in the target area, leaves the skin blackened, and shows virtually no detail.

Once a print is developed, the impression should be photographed with and without photographic scales. Lifting of the print can be done using light-viscosity polyvinylsiloxane (PVS). This takes approximately ten minutes to dry if the body is warm (room temperature). It takes much longer if the body has been refrigerated or is in a cold environment. After it has been captured, the lift impression should be stored in a cardboard pill box with the appropriate case identifiers. The box should be sealed with tamper-proof evidence tape.

Iodine fuming

Iodine fuming is a chemical process that is applied directly to the target area by the forensic technician. The iodine fuming technique was developed by document examiners to locate latent impressions on documents of a sensitive or historic nature. The process yields similar results as obtained in ninhydrin processing. Processing by iodine fuming is non-destructive to documents unless a fixative is utilized to stabilize the impression.

The tools and equipment needed to accomplish the processing are:

  • Iodine Fuming Stix that are sold by the Lynn Peavey Company and other distributors
  • Stick-on photographic scales
  • 35 mm digital SLR autofocus camera, 60 mm micro AF lens, and an independent flash with off-camera TTL flash extension cord

The technician using the iodine Fuming Stix places the tube in his hand, making a fist around the tube. This position allows for a transfer of body heat into the iodine crystals, thus activating the iodine crystals. The technician then extends the plastic tube from the Fuming Stix within inches of the target site and blows the fumes onto the target area. The process of blowing the fumes generates the fumes by activating the iodine crystals with heat and moisture.

Caution should be taken at all times throughout the process due to the toxic nature of iodine fuming. The technician must never take a breath through the fuming tube and people who are assisting need to stay clear of the fumes. The fumes are purplish and the air will smell of iodine.

Once an impression is visible, a photograph of the target site should be taken immediately with a photographic scale. The image will begin to start fading shortly after the fuming has stopped. Reapplication of the fumes is possible, but in most instances is not desirable due to the air contamination.

An effective, powerful technique

The Patricia Scott case was brought to a conclusion by the Chicago Police Department when they developed Gregory Clepper as a suspect in this case as well as in seven other murders. During questioning, Clepper was told that his fingerprint had been discovered under Scott’s bra strap on the left side of her body. (The detectives did not know at the time of the questioning that the print recovered actually belonged to Clepper.) Clepper had initially denied knowing Scott, but when told of the location of the print, he broke down and confessed not only to Scott’s death, but also to seven other homicides.

In closing, it is important to always approach the homicide victim as a crime scene unto itself. The different techniques presented here should provide the crime-scene technician and the investigator with a number of different approaches that can be used at the scene and in the morgue setting. We cannot always obtain success when attempting to ferret out evidence. But as advocates for the victim, we can use the body to act as a witness against the offender.


About the Author

John Louis Larsen served as a Special Agent with the FBI for 22 years and was one of the founders of the FBI’s Evidence Response Team (ERT) program. His last duty assignment was with the FBI’s Chicago Division as Senior ERT Leader. Larsen currently is president of Larsen Forensics, Inc. in Glen Ellyn, Illinois. He has worked as an antiterrorism advisor for the U.S. Department of State. He has also helped the Chicago Police Department and the West Suburban Violent Crimes Task Force develop their own ERTs. Larsen is Senior Forensics Consultant with Quest Con-sultants International, Ltd.; a sworn officer with the Office of the Special Prosecutor of Cook County (Illinois); and a training instructor for Sirchie Laboratories in the use of the Reflective Ultraviolet Imaging System (RUVIS). He also conducts a variety of forensic courses for the Suburban Law Enforcement Academy at the College of DuPage, Glen Ellyn, Illinois.

He can be reached by phone at: 630-469-2016
Or by e-mail at: This e-mail address is being protected from spam bots, you need JavaScript enabled to view it


ORIGINALLY PUBLISHED:
"Prints from Skin," written by John Louis Larsen
May-June 2008 (Volume 6, Number 3)
Evidence Technology Magazine
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