Last week, we had the pleasure to give our friends over at Telus Optik MyVancouver a little behind-the-scenes lesson on forensics:
As with most of the subjects our Programmers share at the Museum, there is always more to say than what time allows. In that spirit, here are a few more bits of info you may find interesting about fingerprints:
Evidence is not always hard to find at crime scenes but when it is forensic scientists look for the more concealed traces that criminals leave behind that connect them to their crime scenes and which can be used in court. One of the investigating tools used is fingerprint identification that can be used even for crimes that are decades old.
Everybody has a unique fingerprint that is not shared by any other person. Every finger pad has a different pattern made up of lines, curves, circles and ridges. Forensic scientists look for general patterns in fingerprints to reduce the number of records needed to search through to find a match. Arches, loops and whorls in prints have patterns that all people share to varying degrees.
Fingerprints remain unchanged through their entire lifetime. If someone burns or shaves the pads of their fingers, the prints may disappear temporarily but will reappear as the skin repairs itself. Severe damage that affects deeper layers of skin may leave permanent scars but completely erasing a print is very difficult and the scars create new distinguishable characteristics that can be used when trying to find a fingerprint match.
The Automated Fingerprint Identification System (AFIS) was created to help scan and digitally encode fingerprints. AFIS stores millions of fingerprint records and information in massive databases. Current AFIS computers search through a batch of 500,000 prints in less than a second.
Fingerprints come in three general types depending on how and where they are found. Patent prints occur when a substance such as blood, ink, or grease on the individual’s fingers left a visible print. Plastic prints occur when an impression of the fingerprint is left in a soft substance such as wax, soap or dust. Latent prints are invisible and need special processing to be seen with either lighting or chemicals that help to expose prints such as cyanoacrylate vapor, iodine fuming, ninhydrin, and silver nitrate.
Quite often, forensics teams are working with prints or partial prints that are very unclear where the unique details may be difficult to see. Digital technology has helped to solve this problem. By scanning prints into a computer they can then enhance, improve, and clean up the computer generated image of the print. Changing the lighting, contrast, clarity, and background patterns can drastically improve the quality and make a previously obscured print jump into clear view, which helps to speed up the matching process and make it more accurate at the same time.
Still not satisfied? Well, check out our forensics programs and other public and school programming. There’s always more to learn.
Big thank you to Laura Shaw for assembling and explaining our fingerprinting factoids for this post!