Introduction to Fingerprints

Dactylography, or the scientific study of fingerprints as a means of identification, is a very important part of Forensic Science. Fingerprints are one of the most reliable sources of individual evidence and they are a staple in most criminal cases when they are found in a crime scene. Fingerprints are a reproduction of friction skin ridges found on the palm side of fingers and thumbs. Friction skin ridges are also found on soles of feet and toes and can also be used to identify a person. Fingerprints are left behind due to sweat, oils, and dirt found on our hands. Fingerprints have been used for centuries to identify people and can be found on nearly every surface. This abundance of evidence littering the surface of so many objects is great news for investigators because fingerprints are considered individual evidence and may provide the key to solving a case.

Fingerprints are even more unique than DNA! No two people have ever been found to have the same fingerprints, whereas DNA can be shared between identical twins! Identical twins are produced from the same egg and sperm and therefore have identical DNA; fingerprints form separately on each twin as a result of amniotic fluid pressure on the developing skin. Additionally, fingerprints are often the way in which identical twins are differentiated in criminal cases. In July 2008, a woman was murdered in Georgia after a carjacking. The police found a cigarette at the crime scene with DNA matching a man identified as Donald Smith. When interrogated, Donald Smith denied that he had anything to do with the murder. When police showed him a video of the carjacking, Donald said that it was actually his identical twin brother Ronald. Authorities questioned his family and they also confirmed that the man in the video was Ronald. Police found a fingerprint in the car and were able to link it to Ronald. When confronted with DNA, video surveillance and a matching fingerprint, Ronald confessed to the crime. If a fingerprint had not been found, Donald could have been mistakenly convicted for a crime he did not commit!

Georgia Virtual, Fingerprints, CC BY-NC-SA 3.0