I had to read up on it again as I had forgotten most of the details.

It seems he was in the wrong place at the wrong time but that's no excuse for lying to the police and I REALLY don't get the part about getting rid of the white suit??? Did the others do the same? Lots of questions and conjecture... no answers. But, he didn't buy a knife and the other two did. Why they bought knives is the biggest question of all for me.