Can forensics do this?

Not definitively. Angle, type of cut, blood under fingernails, fingerprints on the knife etc. could indicate that the cuts were probably self-inflicted or not, but unless the wounds are such that they couldn't be self-inflicted (say a knife in the middle of the back) there really wouldn't be any solid proof one way or the other.

Something that would make a difference too is how many test cuts there are. If a person is trying to kill himself by cutting, a lot of times they give it a few tries, making shallow cuts before going deeper and deadly. That might be something to look for.

They would assess the injuries for the probability of their being self-inflicted according to what is known about self-inflicted injuries, eg that someone who is right-handed will tend to injure the left side of the body, that the injuries will be similar in type and appearance and so on. But it will only be an opinion based on evidence, not a certainty.

Understand that a medical examiner only testifies to medical probabilities, i.e., that such and such a wound is consistent with a self-inflected injury because of whatever facts support that opinion.

The human body has a certain range of motion. For example, you can't touch your elbow with the fingers of that hand. Using that knowledge about range of motion, a medical examiner can identify what injuries someone can inflect on themselves. Further, using their knowledge of range of motion, they can identify wounds that are inconsistent with the probable position of an attacker. For example, although it is possible, it's harder for an attacker to place a knife and cut the inside of the wrist (it's doable, but not easily).

However, people are creative. Tell someone it's impossible to stab yourself in the back, and someone will figure out how to do it. And if you're an attacker, especially with some level of knowledge, you can make sure the indications show the injury is self-inflected.

As a result, the medical examiner is limited to discussing probabilities. Some suicides are actually murders and some murders are actually suicide. Whoops. If you're a medical examiner, you just hope it doesn't happen to you.

Best of luck,

Jim Clark-Dawe

Reservoir Angel said:

Just a minor factual thing I want to clear up:

Can forensic investigation figure out if cuts on a dead body were self-inflicted or not?

Click to expand...

Yes. When someone cuts themselves the cuts are different. After the initial cut it tends to get shallower as someone pulls away. A cut made by someone else - someone not feeling pain - would be deeper and more consistent throughout.

Forensics will also be able to determine what type and the size of blade did the cutting, the age of the injuries and the technician would have an idea of whether or not the injury was treated.

Self-inflicted injuries - gun shot, hitting and cutting - are different from those inflicted by someone else.

See JCDs post - "probably".