Let's say that a person, we'll call him Bob, decides to go out and kill someone. The police hear about the murder, but they can't figure out that Bob was the killer.
A few weeks later, Bob still hasn't been found out. However, something happens to Bob (could be an accident, stroke, etc) and now he has a severe case of amnesia.
He doesn't remember that he killed anybody at all, and goes about his daily life after recovering.
The police later discover that Bob committed the murder, and promptly arrest him. Bob is very confused, and doesn't recall killing anybody. But yet, he did in fact carry out the murder.
Is Bob guilty of the crime he doesn't remember committing?
If a location is necessary to answer the question, we'll say that he resides in the United States.