But there might well be known previous that you don't know about because of the media restrictions that have been in place since he was charged.
"And no, on the whole someone who has no known history of violence does not generally wake up and go out and kill someone."
On what basis are you making this claim? You say it over and over, but what is your evidence for it. It's quite a bold claim, so I'm presume you have read some studies that indicate that people who have previously never been violent rarely commit murders.
He didn't just "wake up and go out and kill someone". He killed her in the evening, so presumably had been awake for many hours. If he murdered her (and I believe he did) he wasn't a murderer when he woke up. He became a murderer after he killed her. It's the act of murder that makes you a murderer.
The idea that murderers are just people wandering around looking for murders to commit is bizarre.
That he had no history of violence (if that is true) is irrelevant. As it would be if he had a long string of convictions for violence. Neither has anything to say about whether he committed this crime.
"Yes he may have some previous violent history but evidence hasn't pointed to that."
Evidence can't point to that. You can't make a case that someone is guilty by pointing to previous convictions. In very limited circumstances (e.g. if he had a history of killing strangers by strangling them) they might admit that into evidence. But there could well be a violent past that is not being brought into evidence because it is not admissible.
"how it is that a 32 year old man who was seemingly not violent suddenly killed a woman within the space of twenty seconds and apparently intended to do so."
Why did a 32 year old man who was "not violent" have his hand(s) around the throat of a woman he barely knew?
We know 2 things for sure about Vincent Tabak -
- He certainly has the capacity for violence (as proven by his strangulation of Joanna Yeates)
- He lies to get himself out of trouble