Teenager, 16. On the spectrum. Dealing with lying etc

Always a problem with this - determining whats bad teenage behaviour and whats aspergers....
 
He plays on his PC a lot. More than we'd like but its his safe zone and calms him down - mostly. In the past, hes got very annoyed and smashed cupboards, thrown chairs etc in his bedroom. We moved the PC downstairs so we could keep an eye on.
 
Hes been good for about a year so we let him move back upstairs to his bedroom. HOWEVER, he told us a few weeks ago (before he moved) he'd broken a glass. Theres more to it. We found pieces of glass the other side of the room, all in his little sisters (whos 6) toy box. Also, there is a strange dent on the wall. There is more to this glass breakage and 99.9% certain hes thrown it.
 
If hes lost his temper thats fine. But he's left glass everywhere. 
Also we asked him about it and he immediately started getting VERY VERY aggressive. Thats his way. He feigns indignation that "no-one ever believes me" and then tries to front it out - but if I had a pound for every time we'd had this and hes later been found out I'd be a zillionaire.
 
Of course, hes made it 10 times worse now by not only continuing to lie about it but get aggressive (this is a big NO in our house - we've had VERY bad experiences with him getting violent in the past)
 
Thing is what do we do? Speak to him again and it WILL escalate. Let it go and it WILL happen again. He'll know he can "front it out" by denying all knowledge because he knows if he kicks off we'll back down.