Anton Roland de Klerk (Antonroland)
Post Number: 11
|Posted on Tuesday, October 30, 2007 - 07:01 am: ||
Must agree here!
In this modern age of wonderful toys a THOROUGH visual inspection is still as important as always.
My personal opinion is that any powder should be used as an absolute last resort.
Andrew Reitnauer (Areitnau)
Post Number: 8
|Posted on Thursday, October 25, 2007 - 12:41 pm: ||
I believe that the best way to process CDs is to 1.) perform a visual examination, 2.) Super glue fume the item, 3.) use a fluorescent dye stain (e.g. Ardrox) to view the latent print.
WANDA WHITE (Unregistered Guest)
Posted From: 220.127.116.11
|Posted on Wednesday, October 24, 2007 - 01:03 pm: ||
WHAT IS THE BEST WAY TO PROCESS CD'S OR DVD'S?
|Posted on Friday, February 17, 2006 - 03:24 pm: ||
I am looking for information on Fingerprints etched into aluminum. What reaction is created in this process? what chemical influence the Reaction? If these fingerprints can be lifted by Black Powder?
|Posted on Saturday, February 14, 2004 - 02:19 am: ||
You got what you needed, but I'll add an experience from a recent case. The twist is that the perp, probably under pressure from a friend of the victim, carefully cleaned and wrapped all the stolen property and left it in the victim's driveway. No prints. BUT - somewhere along the line, the crook or an associate mistakenly? put a home-made rap music CD into one of the many returned DVD movie cases. That CD yielded two clear finger impressions with cyanoacrylate and mag powder.
|Posted on Tuesday, February 10, 2004 - 11:03 pm: ||
Thank-you for the replies on this topic. I essentially wanted to have clear confirmation that obtaining the fingerprints (with or without damaging the CD) was not a complicated procedure. I'm just a member of the public who was forced to take a police officer's statement at face value.
To answer one question, the CDs are just music ones, and a couple were damaged anyway, so I am willing to lose a CD in pursuit of the fingerprints.
Your advice will allow me to talk to the Senior Sergeant of my local station regarding his officer's palming me off, excuse the pun. I will also ensure they try to get the prints.
|Posted on Tuesday, February 10, 2004 - 10:41 am: ||
There is a cleaning solution that makes it possible to process CD's for latent prints by cyanoacrylate fuming and then 'clean' the surface of CA residue without damaging the audio/recording quality of the CD's contents.
|Posted on Tuesday, February 10, 2004 - 06:15 am: ||
I failed to address the comment you heard that "the CD isn't flat." The top of the CD is flat and the bottom is also flat. The police officer may have somehow assumed that tiny grooves are etched into the bottom surface of the CD during recording. The laser beam recording the information penetrates through the bottom surface, leaving it completely smooth. That said, even real grooves pressed into 45 rpm, 33 rpm, etc., records do not prevent identifiable latent prints from being developed on those relatively smooth surfaces.
"Jump" wrote that if it is okay to ruin the CD, simple black powder will in most cases be all that needs to be done.
If that advice is followed, police will probably miss 50% of the identifiable latent prints present on the CD. Here is why (from the FAQs at this website):
Ask the average policeman who comes to your house what is left behind in latent fingerprints and he will probably say "oils." That could happen if the burglar were eating fried chicken, just put on Vitalis, or was rubbing his oily face... but, oil and fatty substance secreting glands on the human body (sebaceous glands and apocrine glands) are NOT present on surfaces lacking hair... that is, NOT on finger, palm or barefoot friction ridge skin. A slight amount of trace oil can sometimes be present because of "flow" on the skin surface from the back of the hand to the front, but such oil is only a slight trace compared with the oil you get on your fingers from rubbing your nose or forehead. Natural secretions from the sweat secreting glands (called eccrine glands) on fingers and palms (and bare feet) secrete NO OILS. They secrete about 98 or 99 per cent water, and the solids dissolved in the water include amino acids, proteins, polypeptides, and salts.
If you want to duplicate the basic effect of fingerprints on evidence, clean off a rubber name stamp so it leaves no ink traces behind. Next dip it into a solution of chicken broth. Shake off the excess liquid and stamp the impression on a drinking glass. Within a few minutes the liquid will dry and the impression will be almost invisible. Make another test impression on a piece of paper and let it dry. Unless you happen to have oily chicken broth you have just roughly (very roughly) duplicated the natural secretions present in latent fingerprints at crime scenes. Some researchers have compared dried eccrine gland secretions to a very faint coating of dried "shellac."
Latent fingerprints on glass, paper, or similar nonporous surfaces should be chemically processed to develop the best quality (greatest contrast) ridge detail. Picking up the glass with a handkerchief around your hand would destroy the test print... so would putting it in a plastic bag or envelope to carry it to a crime lab. Doing the same with the paper would not harm the test print there because it has soaked down into the paper fibers. Dusting the glass with fingerprint powder will probably destroy the latent print (there's usually no oil for it to stick to) and will almost never give the excellent results possible with chemical processing. Without chemical processing, the best you could probably do would be to "rejuvenate" the impression on the glass by breathing on it and then dusting with powder immediately after you see the "fogged" area on the glass evaporate. The moisture from your breath will leave the ridge detail slightly moist for a short while and increase the chances of fingerprint powder sticking to the non-oily print.
Many police will remark that a certain surface cannot be processed for fingerprints. Any surface that is about as smooth as the miniature corrugated cardboard type ridges on your fingers can potentially bear identifiable latent fingerprints... and the flexibility of the finger skin can often also conform to relatively rough surfaces such as imitation leather dashboards. Fingerprints from crime scenes have been identified on papers, cigarettes, fruit, crumpled aluminum cans, plastic garbage bags, bed sheets, dead bodies (prints on bodies are usually contaminated prints involving body fluids, lipstick or some other substance transferred via the suspect's fingers), and thousands of other surfaces. Fingerprints on paper, cardboard and unfinished wood can last for up to forty years (per actual casework histories) unless exposed to water (and contaminate transfer prints can even then sometimes persist). Fingerprints on non-porous surfaces such as plastic, metal and glass can last for years if not exposed to water and if left undisturbed.
|Posted on Tuesday, February 10, 2004 - 05:33 am: ||
Are the CD's you are talking about music CD's or ones containing important information. In other words, it is very easy to develop latent prints on CD's but there is a chance of ruining them in the process. If the CD can be easily replaced and you have no problem with it possibly being ruined, then simple black powder will in most cases be all that needs to be done.
|Posted on Monday, February 09, 2004 - 07:27 am: ||
It is very easy to develop latent prints on CDs.
The discussions about CDs in this forum have to do with damaging the content of the CDs during processing.
|Posted on Monday, February 09, 2004 - 02:43 am: ||
I was recently told by a member of the Australian police force that they could not lift fingerprints from CDs of mine that had been stolen and found. He said this is because the surface of the CD isn't "flat".
I questioned this blank statement of "it can't be done" - most particularly because it is the only forensic evidence I have from multiple and repeat offenders. I suggested that there must at least be some kind of digital imaging possible - whereby photographing the CDs would produce viable images, for example. No Australian police force has such technology, apparently. I cannot for a moment believe that no police force in Australia would at least _attempt_ to lift the fingerprints.
Having read some of the postings, it is clear that there is some issue regarding the lifting of fingerprints from CDs. What I would like to know is: what IS possible? I have very clear fingerprints on several of the stolen CDs. There must be something that can be done?