Bodies in various stages of decomposition can be very difficult to identify. The pathologist may take x-rays of dentition or other areas. They may search for serialized medical devices like pacemakers, breast implants, or stabilizing plates. Of course the best method for identification is the fingerprint. Fingerprints are unique and permanent (meaning the patterns don't change during life unless seriously injured). making them ideal for identification. Most people in the United States have been fingerprinted to some degree. The most common fingerprint record is the single fingerprint found associated with the driver's license. CSIs can also search for fingerprints on the victim's belongings (in their home, office, or vehicle).
But what do you do when the fingers have become shriveled or dried out during decomposition? Fingers can become shriveled in a day or two depending on the environmental conditions. The skin is still intact but it contracts and becomes rigid. This condition makes it almost impossible to get good quality impressions. The best way I can describe it is the difference between a raisin and a grape. So the real question becomes...how do you turn a raisin back into a grape? One method is the use of Photo-flo 200.
Photo-flo is a Kodak product used in rinsing photographic film during the development process. It's kind of like a really powerful soap. I'm sure the engineers at Kodak never envisioned how CSIs would someday use the solution. CSIs love to come up with new uses for products we have easy access to and this is no exception. To star the process we have to sever the finger or fingers we want to restore. The fingers are then soaked in the Photo-flo for anywhere from 24 hours to a week depending on how bad their condition is. The main objective is to get the tissue pliable again.
Once the tissue is pliable we have to inject a gel called "tissue builder". This is a semi-clear viscous material resembling epoxy (although not sticky). The tissue builder is injected under the skin using a syringe. The material expands the pliable skin, stretching it out to it's "normal" condition. Once this is done the finger can be rolled just like it would be in life. It only takes one good finger to make an identification so we have to check their records to see which ones might be the best to use. Once that is done it is a simple matter of comparing the fingerprint patterns and ridge detail to make an identification.