Prints on US Currency:

    Although at time it can be difficult, latent prints can be developed on US currency. US currency is not paper, but rather composed of fibers so that it is closer to a fabric.  That is why the currency usually holds up well after being immersed in liquids.

    The currency (bills) is first immersed in Ninhydrin, allowed to dry and then let set for 24 hours. (Ninhydrin reacts with the amino acids present in the perspiration.) After 24 hours the currency is examined for latent prints and if any are developed they must be photographed (cannot be "lifted.") Subsequent to that, the currency is processed with live steam by slowly passing over the bills with an ordinary steam iron, set to "steam." This will in many instances darken those latent prints that are visible and at times develop additional latent prints that were not visible. As before, these latent prints must be photographed to preserve them.

    Following the Ninhydrin process, the currency, after being immersed in a Maleic Acid bath for a few minutes, is immersed in Physical Developer (PD) which will react with the lipid fats and waxes present in the perspiration. Lipid fats and waxes will usually last longer than amino acids in the perspiration, therefore this method will also develop latent prints that are very old -- perhaps years. (PD was originally formulated to develop latent prints on paper items that had been wet and is also valuable in those instances)

    After the PD process, the bills are rinsed thoroughly in tap water and allowed to dry.  Any latent prints, like those developed with Ninhydrin, must be photographed. Finally, I recommend that the bills then be immersed in a solution of 20% -- 30% combination of common household bleach and tap water (20% -30% bleach and 70%-80% water), then dried thoroughly. This will enhance and darken those latent prints that were developed with PD.

    If your agency has access to a laser, US currency can also be processed by immersion in DFO.  After the specimens are dry, they should be subjected to dry heat, such as being placed in an oven set to 100 degrees C.  If an oven is not available, a dry iron may be used; for instance a steam iron with the steam function turned off.  Remember, even though DFO is a Ninhydrin analog, it is subjected to DRY heat after processing, not live steam as is the case with Ninhydrin.  After this, the currency is examined with a laser or alternate light source and any latent prints are then photographed.

    After DFO, as with Ninhydrin, the currency can be processed with Physical Developer.  I have not found it worthwhile to use both Ninhydrin and DFO.  The best method is to use one or the other, then follow with Physical Developer.

Adult/Child Differences

Basically, size is the only discernable difference between an adult and a child's fingerprints (palm prints, footprints). Of course, this will depend on the age of the child and the hand size of the adult. An infant's fingerprints will be so small as to be obvious. A physically large child of ten or eleven years might have fingerprints about the same size of a very small adult.

The ridges, their characteristics (ridge endings, bifurcations and dots) and their relationship to each other are fully formed about four months before birth. The fingerprints you have now as an adult are the same ones you had before you were born. The only difference would be due to some sort of trauma (burning, scarring, amputations, etc.) or disease. Even then, the result is the obscurring of the ridges, not a re-arrangement.

The reason that in the first sentence I used the word "basically" is that there can be some subtle differences between an adult and a child's fingerprints other than size. As a person ages, the ridges tend to wear down (to a greater or lesser degree, sometimes depending upon the person's occupation) and lose some of their elasticity. Also, creases in the surface of the fingers, hands and feet will deepen and widen. That is why that at times, it can be difficult to record the fingerprints of elderly individuals.

As a side note, it is not possible to determine sex or race by the fingerprints. Any determinations would only be guess work and not based upon any hard science.

Can Fingerprints Be Taken Off of Skin?

Yes, it is possible to obtain latent prints from human skin. Although, due to various physiological reasons, it is difficult, there have been instances in which latent prints were developed on human skin and subsequently identified.

The process can range from the use of iodine fumes to direct appication of magnetic fingerprint powder to subjecting the entire body to cyanoacrylate fumes, applying fluorescent fingerprint powder or liguid dye stains, then examining with a laser.

There are a number of problems that reduce the chance of developing latent prints on skin. First, there must be friction ridge skin contact to relatively smooth skin (neck, face, underside of arms, etc.) As skin is an organ, it will absorb and/or dilute the perspiration from the friction ridges that form the latent print. There seems to be more success in developing latent prints on human skin if the body was deceased when handled.

The body/victim must be examined as soon as possible. Additionally, the latent print examiner must be trained in the process of developing prints on skin.

There is one process that I personally believe is sometimes overlooked when examining female victims of assault. If an assailant approaches the victim from behind and holds his hand over the victim's face while controlling her with the other, it can occur that the fingers can contact make-up and/or lipstick. This can coat the ridges and then when another part of the body is touched, these substances can cause a print to be transferred. Examining the body with a strong light or laser can reveal one of these prints. Although finding a latent print on human skin in this manner is rare, it should not be overlooked, especially if the aforementioned circumstances occured.

Are All Fingerprints Different?

Yes, the arrangement of the friction ridges on each finger of each individual is different; that is, no two individual fingerprints are alike. The arrangement of the ridges on your fingers are all different from each other and different from any other person.

That is why a latent fingerprint that contains only a fraction of the total characteristics (ending ridges; bifurcations; and dots) present in a fully recorded inked fingerprint can be identified. This same principle applies to the friction ridges present on other areas of the fingers and palms as well as the soles and toes of the feet. (No two palm prints, footprints, toe prints, etc. are alike).