| Author | Message | ||
     Liana |
Can you help me? i need to know what surfce you use amido black on | ||
| Webmaster |
Initially answered by the Webmaster (directly via e-mail) on 27 JUN 01: Do you have a RUVIS device for real-time short-wave UV reflection examination (not a UV luminescence method)? Your four-knife research sounds very interesting and innovative. I suspect the surviving test print may have been in sebaceous matter versus eccrine gland secretions. You at least have a chance of similar success with a sebaceous or other oily contaminate type latent print if you use that technique on the remainder of the heavy deposits on the blade. Of the three blood techniques you mentioned, I prefer Amido Black, although DAB (3,3'-diaminobenzidine) is also known to work well on such surfaces. Hungarian Red (acid violet 19, fuchsin acid) is perhaps not as well suited for a non-porous surface, per Sandridge UK research (Enhancement of Fingerprints in Blood - Part 2: Protein Dyes, by V.G. Sears, C.P.G. Butcher, T.M. Prizeman, JFI 51(1), page 34). I have used the following sequence well, but it does NOT take into consideration the mechanical "lifting" you did to reveal latent print ridge detail beneath a dry, heavy blood deposit: 1. Visual exam including normal lighting, oblique lighting and direct reflection NOTE: Photographic recording of faint bloody ridge detail using direct reflection on a non-porous plastic surface can be very important at this step... it may capture better ridge detail than all subsequent procedures... and some of the subsequent procedures may deteriorate ridge detail 2. Luminescence exam (sometimes black plastic police night-sticks will luminesce yellow revealing excellent dark ridge detail in blood which is quenching the luminescence) 3. RUVIS exam (DNA samples should be collected prior to short-wave UV exposure of blood deposits... actinic lighting can damage DNA) 4. Cyanoacrylate fuming (don't over-fume/create heavy deposits, of course) 5. Visual exam (normal, oblique and direct reflection with white light) 6. RUVIS exam (faint cyanoacrylate deposits can sometimes be better visualized with RUVIS than via luminescent dye staining) 7. Rhodamine 6G in methanol (or other dye stains suited for your excitation light source... the methanol should fix the blood on the handle, if it can be fixed any more than the cyanoacrylate fuming achieved) 8. Luminescence exam (exciting dye-tagged ridge detail) 9. Amido black 10. Visual exam (normal, oblique and direct reflection with white light... though the oblique and direct reflection viewing will probably not yield anything new) 11. Luminescence exam (again checking for a quenching effect) 12. Dusting with a contrasting color powder 13. "Rubbing" with a contrasting color powder (first documented by Grimm and Taylor, Identification News, March 1984, Vol. 36(3), page 7) this can sometimes reveal ridge detail completely invisible via all the prior techniques) In your specific instance, I suspect the handle may give up the best quality impressions. --Ed German | ||
| Webmaster |
Initially submitted to the Webmaster on 27 JUN 01: I am attempting to develop latent fingerprints and/or fingerprints in blood on the knife. The blade is stainless steel and the handle is black plastic. There is a lot of blood on the blade and very little blood on the handle. So far I have examined the knife for latents/blood prints using the polilight - nothing visible. I have also treated the knife with cyanoacrylate - nothing visible on the handle, small area of unidentifiable ridge detail developed on the blade (close to the handle where there was no blood present). This area of ridge detail stops where the blood on the blade starts i.e. it is likely that the latent print continues on underneath the blood. My question to you is do you have any experience with, or know of any way of removing the blood from the blade and not damaging the possible fingerprint underneath the blood? The blood is reasonably thick in some places and thinner in others. I have not used sulphosalicylic acid or any other blood fixative in the hope that there may be some way of trying to remove the blood. The blood isn't particularly flaky, but it is dry. I have tried a rough experiment on 4 similar knives by placing my latent prints on the blade of the knives, then pouring animal blood over the blades and leaving the blood to dry overnight. I then tried soaking knife 1 in water, knife 2 in cyclohexane and knife 3 in HFE 7100. The water dissolved the blood but left no fingerprints underneath. I also tried spraying the blade with SPR after soaking in water but no prints developed. The cyclohexane appeared to fix the blood onto the blade rather than removing the blood. The HFE 7100 wasn't very effective at removing the blood either. On the 4th knife I tried lifting the dried blood off using an ordinary fingerprint lifter - This worked well and left a good quality latent print underneath. On the 4th knife I also tried lifting the blood off by using a BVDA shoeprint lifter - This appeared to lift the blood and some of the ridge detail off as well. It left partial prints in blood on the blade, but these were not of very good quality. Based on these results I attempted to lift the blood off a small area of blade on the actual exhibit using an ordinary fingerprint lifter and then a shoeprint lifter. Both attempts were unsuccessful. Most of the blood still remained on the knife. Do you have any advice on what I should do now? Do you think it is worth trying to remove the blood or would you just continue with blood treatments such as DAB, Amido Black, Hungarian Red etc? I have used panacryl on the handle of the knife only - no prints developed. |
