Threat Mail and Forensic Science: DNA Profiling from Items of Evidence After Treatment with DFO

Abstract

Two cases of threatening letters with their accompanying envelopes were received to the Division of Forensic Identification unit of the Israel Police. The envelopes, including the stamps, and the letters were initially examined for latent fingerprints by the DFO reagent, known to cause degradation of DNA. Although no latent fingerprints could be visualized on any of the items, the biology laboratory using organic DNA extraction, was successful in defining genetic profiles from all the items employing six STR loci, even after treatment with DFO. In a controlled experiment, a known donor attached a stamp, by licking, to an envelope. This item was treated with DFO and then profiled using STR loci. The results showed that previous DFO treatment on the control stamp before DNA analysis had no negative effects on obtaining the DNA profile of the known donor using STR loci.

Forensic DNA Analysis

“…No interference Grubwieser et al 2003 Ninhydrin No interference Stein et al 1996;Fregeau et al 2000;Grubwieser et al 2003;Anslinger et al 2004 DFO (1,8-diazafluoren-9-one) No interference, except there may be an incubation time and extraction method effect Fregeau et al 2000;Zamir et al 2000a;Grubwieser et al 2003 RTX (rutheniumtetroxide) No interference Grubwieser et al 2003 Gentian violet No interference Stein et al 1996;Grubwieser et al 2003 Enhancement of blood traces…”

Recovery of DNA Profiles from Fingerprints on Paper after the Application of Ninhydrin or DFO Given Certain Time Periods

“…She also states that ninhydrin, DFO, black powder and white powder do not interfere with DNA typing [51]. This is confirmed from several researches in the past [40,41,52].…”

“…The fingerprint is developed by reacting to the amino acids in the fingerprint residues on dry porous surfaces [39,40]. The finished product of DFO needs heat and the fingerprint is observed using a specialized light source.…”

“…The finished product of DFO needs heat and the fingerprint is observed using a specialized light source. DFO was used in research for potential threat mail before being used for DNA analysis [40]. They did find that DFO did not interfere with DNA analysis and a successful DNA profile could be obtained.…”

"Queiloscopia: uso da técnica na identificação forense"

“…A diazafluorenona ou DFO trata-se de um poderoso reagente de papel e superfícies porosas, atuando de maneira similar a ninidrina, reagindo com aminoácidos e possivelmente com outros compostos da impressão labial (ZAMIR; OZ; GELLER, 2000). Entretanto, seu mecanismo de reação e sua sensibilidade são diferenciados da ninidrina, recomendando-se seu uso antes desta (ÁLVAREZ, 1999).…”