An article published in Current Biology this week describes a recently developed way to use blood drops to determine age. This capability will most certainly be useful in developing a profile of victims or criminals in cases where blood is a part of the evidence but identity is unknown. The BBC article: test tells age from blood drops.
The technique utilizes a specific type of immune cell, called a T cell. This is a significant development because to date the information contained in a blood sample can only be used to confirm the identity of a known person. With this new technique, researchers can describe characteristics of an unknown person to help identify them.