Fluorescing Fingermarks

Several fluorescent dyes are used for the direct detection of fingerprints and/or the enhancement of superglue fumed fingerprints. All of these dyes fall into the category of lysochrome dyes. In general, they adhere to lipophilic surfaces with Van der Waals forces. The great advantage of using fluorescent dyes is that the fingerprint ridge detail can [...]

Suddenly Sudan

Oil Red O, the subject of a previous post, is just one of several fat soluble (lysochrome) dyes that are used in fingerprint revelation. Sudan Black is another popular lysochrome dye which is especially useful in developing prints on waxy paper and wetted surfaces. Apparently, Sudan Black refers to Sudan Black B, a member of [...]

As Good as Gold

Vacuum metal deposition (VMD) is a technique that has found some popularity despite its rather great expense. Initially, a sample of gold metal is evaporated in a chamber containing the object to be fingerprinted. The gold atoms are deposited on the latent fingerprint residues preferentially to the surface on which the fingerprint lies. This is [...]

Oil Red Oh

A hydrophilic dye called Oil red O has attracted some attention recently as a good compound to reveal latent fingerprints on difficult surfaces. Alexandre Beaudoin in a Journal of Forensic Identification article entitled “New technique for revealing latent fingerprints on wet, porous surfaces: Oil Red O” proposes that oil red O is a good alternative [...]

A Crimefighter Called Ruth

Ruthenium Tetroxide (RuO4) is an inorganic oxide that has found its way into fingerprint residue revealing literature. Ruthenium Tetroxide even has a racy alias: RTX. As far as I know, it is not widely used. I ran across it in a recent Patricia Cornwell novel: Book of the Dead. Subsequent to this discovery I found [...]

Underwater Fingerprint Detection

Small Particle Reagent is used to detect latent fingerprints left on wet surfaces. The reagent is made of a suspension of fine molybdenum disulfide in a surfactant solution. Apparently, the particles adhere to the water insoluble fatty residues of fingerprints. Other materials besides molybdenum disulfide can be used as well: titanium dioxide, zinc oxide, magnetite [...]

Super Cyanoacrylate Esters

The cyanoacrylate ester fuming method of revealing fingerprints was discovered by the Criminal Identification Division of the Japanese National Police Agency in 1978. It was soon practiced all over the world. Amazingly, fingerprint residue exposed to cyanoacrylate ester fumes for brief periods of time become harden tan-colored fingerprint impressions. There are three different esters that [...]

The Sticky Side of Life

Given, the importance of developing latent prints on the sticky-side of tape, several methods for revealing them. Much like the “dusting” method of latent print revelation, a series of sticky-side wet powders are available. Generally, these are dry powders which are suspended in an aqueous solution with an anionic surfactant. Very likely the forces to [...]

I Got This on Tape

There a several methods to reveal latent prints on the sticky side of tape. Why is this important? 1) Tape seems to play an important part in some crimes: abductions, for example. 2) It is difficult to tape something without leaving a fingerprint on the sticky side at some point. 3) It is almost impossible [...]

The Silver Lining in Latent Print Revelation

The use of silver nitrate (AgNO3) to reveal latent prints is a very simple technique has been practiced by law enforcement since the 1930′s. According to the FBI website, the technique was first used in the United States to solve the 1933 kidnapping of William A. Hamm, Jr.,  President of the Theodore Hamm Brewing Company. [...]