Forensic Evaluation Skill
The Forensic evaluation skill serves 2 purposes when it is activated from the skill list;
When you target a corpse, you can find out who killed it and who has tampered with it (by tampering we mean opening it with a double click or cutting it with a knife). If someone has tampered with the corpse, that does not necessarily mean they looted it (took what was on it).
When you target a player, you can find out whether that player is a member of the thieves guild.
Forensic evaluation is also used to identify the owner of lost equipment - looted equipment marked as a "Lost Item". For the greatest benefit to your Honesty virtue, return the lost equipment directly to its owner.

To raise the Forensic evaluation skill, use it on corpses over and over.