In a movie I recently watched, a rather convoluted murder took place. As a matter of fact, it was so convoluted that I have no idea if the character was guilty or not. I'll try my best to keep the details vague so as not to provide spoilers.
Person A is a medical professional, caring for person B. In A's medical bag there are two different flasks of pills; one that helps treat B's condition and one that would kill B. After administering the pill, A takes a look at the label on the flask and notices that he accidentally gave B the lethal pill, not the beneficial pill. Apparently, B is not very concerned with his own death, and moreover believes that A made a honest mistake and is fond of A. Hence, B comes up with a plot to make his death look like suicide and A reluctantly agrees to participate. The plot involves B commiting suicide, and A going through a number of deceptions in order to secure an alibi, but nothing else that would normally be illegal (at least with B's permission). The plan is put into motion, and B indeed dies by his own hand.
The big twist is that the main villain has, unbeknownst to A and B, mislabelled the two flasks with the intention of killing B. The pill that A gave B would not have caused any bad effects, and B would have lived if the cover-up plan was not executed.
Clearly, the villain is guilty. But what about A? Has he committed any crimes? Is he guilty of accidenatally causing B's death? Or possibly obstruction of justice?