Recovering fingerprints from human skin was all but unheard of when I started working in the late 1980’s, however, recent attempts have found that obtaining viable fingerprints in real world situations shows some success, albeit extremely limited.
Victims of homicide are often touched or moved by their killers; knowing this, but being powerless to obtain usable fingerprints from the victim is frustrating to say the least. It is very rare to get usable fingerprint evidence off of a murder victim, but the practice has evolved, and it’s possible to collect fingerprints from the skin of a murder victim.
Human skin is far from the ideal medium for the development of fingerprint evidence, it is pliable, and porous, and upon death, it releases fluids and gases, making it an extremely poor surface in itself.
Additionally, during an original response by first responders, the victim will almost surely be touched and moved by well-meaning officers or EMT’s as they try to determine the status of the person. This could be followed up by hospital personnel doing the same, if the victim was transported from the scene to an emergency room. In cases where the victim was not transported from the scene, you still have to factor in that many people might handle a body while checking for evidence, and by removing the body from the scene; all of which can destroy existing fingerprints to the victim’s skin.
Since the stakes are so high in a death investigation, researchers and real world experts have continued trying to successfully locate and document fingerprints on homicide victims, and have made some successful strides.
The FBI has been involved in research on methods to develop identifiable latent prints on human skin for decades, as FBI forensics personnel began researching the possibility of recovering latent prints on dead bodies in the 1970’s.
The FBI was able to obtain positive results in a controlled environment by using a superglue fuming onto the skin of embalmed bodies, up to days after the prints were deposited. Keep in mind that these prints were carefully deposited, carefully preserved until processing, but the fact that they were successful at all helped guide others in the process.
Later research found that latent prints could be developed on bodies in the laboratory setting that were more realistic; these experiments used bodies that had not been embalmed, and the method of depositing the prints was more consistent with what would be encountered in the real world. Research showed positive results up to about 1 hour after the prints had been deposited.
Subsequent experiments found that using a superglue process, coupled with the application of magnetic fingerprint powders, yielded positive results. The research found that the superglue processing time was the most critical part of the process. The amount of time the superglue fumes were in contact with the body would be the most important factor, and most any powder or dusting process used would yield positive results as long as the fuming time was correct.
Having been successful in a controlled environment, researchers then wanted to move onto making the process work in real life. The first step was to try and incorporate realist settings to the equation, knowing that real life scenes are never set up as a laboratory environment. Researchers would then begin try to simulate conditions that showed a body exposed to the elements for days, and varying the temperatures of the bodies, and they were still able to obtain positive results, if proper collection procedures were used.
At an actual scene, when it was believed that the body had been touched, the process would better be performed at the scene, and not be moved prior to the process. In this scenario, the check would be done only after the inquest had been performed.
Moving the body could ruin any fingerprints prior to them being processed, and subsequent refrigeration of the body would likely cause adverse effects on the collection process. In cases where processing at the scene isn’t possible, the body should be brought back to room temperature, and care should be taken to make sure there is no moisture left on the skin from the warming process.
Studies have shown that skin that is warm, or near normal body temperature, should be fumed for only 5 to 10 seconds. Skin that is colder should only be fumed slightly longer, with 15 seconds being the maximum amount of fuming time. After the fuming process, magnetic powder would be used, and any usable latent prints should be photographed, then lifted.