DFO – Visualization of fingerprints

latent fingerprint

DFO (also referred to as 1,8-Diazafluoren-9-one) is used in criminalistics to make latent fingerprints on porous surfaces visible (mainly on paper but also on photos and cardboard). Furthermore, it can be applied to make slight blood stains visible.

DFO is a Ninhydrin-analogue which provides better results than Ninhydrin alone. If it is used in combination with Ninhydrin it must be used before the ninhydrin. (The detection reaction of DFO is considered as generally more sensitive)

After the DFO is sprayed onto the exhibit it reacts with the amino acids which are in the fingerprints (and also in blood). To make the reaction visible, the dyed exhibit must be warmed up for 10-20 minutes. A blue-green forensic light source brings up a yellow fluorescence which can be photographed quite well with an orange filter.

Latent prints which were made visible with this method can be examined with the UV/VIS ScanKit of EVISCAN and high quality pictures can be taken and processed. Also, the built in image enhancement software and all automated documentation is available – thus, the device is a photographical documentation center for fluorescence-photography just as well.