CSI & Reality

A new study showed that forensic experts are not that great at estimating the age of a bruise--something forensic experts do to estimate the approximate time a crime (such as child abuse and sexual assault) was committed. The median difference between the estimated age and the actual age of the bruise was 26 hours, which could be a pretty significant difference in practical terms.

I do have a question about the study, though. Bruises were created on Caucasian volunteers by using a suction cup. I would think that most assault bruises would be from rough contact. Do bruises created by these different means differ in important ways?