Expert: John Shea - 2/24/2010

Question
I'm not sure if you can help me out with this, but in class the other day we were watching a clip of the show C.S.I. In the clip, a murder was being looked at again from 18 years ago. The crime scene investigators are searching for evidence and they come across a hammer that has grown inside of a tree. They take the hammer back to the lab and discover bloody fingerprints on the hammer. This had me wondering, could a bloody fingerprint really last this long after being stuck in a tree? If so, how, and also how long could it possibly last for?

Answer
Dear Billy
I saw this episode, too.  I doubt that blood could remain intact enough to preserve a fingerprint if it was exposed to atmospheric changes in sunlight,
temperature and humidity.  We archaeologists sometimes find blood residues on artifacts that are hundreds or even thousands of years old, but these
are usually things that were buried quickly or otherwise preserved in stable cold, wet, or dry conditions.
I know that the CSI program has a good team of scientific consultants and that the producers and writers pride themselves on getting the science right.
But, as they say, they are making entertainment, not documentaries.  Unless some other expert or a forensics expert can confirm the possibility of such
long-lasting and well-preserved fingerprints, I would chalk this up to "literary license".
You might look up CSI website on cbs.com and see if there is a contact person to ask about this issue.
Cheers,
John Shea