An Autopsy

1. A dissection performed on a cadaver to find possible cause(s) of death.
2. An after-the-fact examination, especially of the causes of a failure.
3. (rare) An eyewitness observation, the presentation of an event as witnessed.

The term necropsy is usually used for non-human animals, with autopsy reserved for human beings.

(dissection of a cadaver): necropsy, necrotomy; postmortem

(after the fact examination): postmortem