2). Corinnes testimony. I find it hard to believe that she would cover for her son, if she thought that he was responsible for such a heinous crime.
This has never made sense to me either as if we look at johns scenario Luke never went home, we know he never washed up and cleaned himself after a murder at his own house as per forensic's and was waiting at 5:50 on a wall where he was spotted by boys on bikes.
He then mucked about till just after 9 pm and went home, he then received a text and acted on that text within minuets and there are calls/texts to lukes mobile afterwards that clearly show that Corrine had no idea what was going on, these text's call attempts have been retrieved.
If your son/daughter was calling you and trying to explain something so unreal how could you react to that.