You're all wrong. Wrong, wrong, wrong, wrong. No double-jeopardy, no killings in gaol (he hasn't even been in gaol before), the victim was human, the offender is human and not insane, he's not the executioner on account that he wasn't facing execution, an out-dated form of punishment, he was facing life imprisonment - and is not only guilty as charged, but even pleaded guilty! Meaning he was indeed alive for the trial - and we can assume has gone on living quite happily after the trial. There is no war. The murder was not (ruled as) assisted suicide, self-defence, automatism, insanity or manslaughter. The murder was premeditated. He killed his victim in cold blood. He pleaded guilty to this, and he was found to have acted alone in the murder (meaning no one else has been convicted for the murder, and no one else was put on trial for the murder). He was convicted of murder, but will never be punished for the crime.

And no, it was not a mistrial! No come on, THINK...