Aim: To test the VMD technique for its ability to develop fingermarks from spent cartridges and bullet casings. Natural and sebaceous marks to be deposited onto bullet/cartridge by a single donor and the bullet/cartridge fired after a set time period (< 5mins, 1 hour, 24 hours, 7 days, 28 days). Gold/Zinc (AuZn), Silver (Ag), Silver/Zinc (AgZn), Sterling Silver (S.Ag), Aluminium (Al) and Copper (Cu) VMD processes to be tested and compared for effectiveness.
Update: 20th April – deposited <5 minutes before firing
Our first test results are in! I’m pleased to say that all 6 different evaporation metals successfully developed good friction ridge detail on all 12 of the .243 Winchester bullet casing samples containing fingerprints deposited <5 minutes before firing.
The evaporation metals which gave the best contrast and clarity were Gold/Zinc – AuZn (image above) and Silver -Ag (image below).
Update: 21st April – deposited <5 minutes before firing
This time, 12 shotgun cartridge samples containing the same donor fingerprint as the bullet casings, deposited <5 minutes before firing, were processed. Yet again the VMD worked its magic and good friction ridge detail successfully developed on all 12 discharged cartridges.
All 6 evaporation metals developed marks well, however, again Gold/Zinc – AuZn (bottom image) and Silver -Ag (left image) worked well along with Sterling Silver – S.Ag (right image). The Gold/Zinc process worked particularly well on both the plastic and metal
Update: 5th May – deposited 1 hour before firing
The results of fingerprints deposited 1 hour before firing on the .243 Winchester bullet casings were similar to the previous >5 minute depositions. Yet again, Gold/Zinc – AuZn (image left) and Silver -Ag developed the best contrast and clarity.
However, the results of fingerprints deposited 1 hour before firing on the shotgun casings were more interesting. Gold/Zinc – AuZn developed well on both the brass and the plastic compared to Silver -Ag and Aluminium – Al which developed detailed prints on just the brass.
Update: 12th May – deposited 1 day before firing
Ridge detail was developed on all the cartridge casings which where processed containing fingerprints deposited 1 day before firing, however, certain VMD metals developed better than others. The Gold/Zinc (AuZn) and Aluminium (Al) process yet again developed the prints well, but this time interestingly Copper (Cu) also yielded very positive results.
Ridge detail was also developed on all 12 shotgun cartridges processed but not all metals were successful on developing on both the plastic and brass.
Copper -Cu (image left) surprisingly yet again developed the 1 day old prints well and on both surfaces.
The Gold/Zinc (AuZn) process continued to develop well and currently looks like the go to process.
Update: 22nd May – deposited 7 days before firing
The VMD continued to development good ridge detail on 7 day old fingerprints with successful development on 92% of the discharged casings and shotgun cartridges. Sterling Silver (S.Ag) worked particularly well on the metal surfaces with Gold/Zinc (AuZn) remaining effective at developing prints on both metal and plastic.
Update: 31st May – deposited 28 days before firing
I’m very pleased to say that our final set of results for fingerprints deposited 28 days before firing show no obvious trend for decrease in quality over time with continued development of excellent prints. Sebaceous marks actually appeared to improve over time which will be key when processing older evidence or cold cases.
Gold/Zinc (AuZn) and Sterling Silver (S.Ag) were the optimal techniques this time for developing good ridge detail on the rifle cartridges as shown below. Note that the Gold/zinc (image left) has produced a -ve image compared to the Sterling Silver (image right) which is a +ve. Another one of VMD’s mysteries yet to be fully understood!
Gold/Zinc (AuZn) developed prints again on both the plastic and metal of the shotgun cartridges resulting in 100% success rate for all 12 cartridges tested using the Gold/Zinc process. Copper (Cu) and Silver (Ag) also continued to developed well on both surfaces.