There's a lot of talk about Adnan loaning his car and cell to Jay on the day of the murder and that was part of his premeditation.
On the flip side to this, noone appears to be questioning whether Jay made sure his car was unavailable that day and the following day (as per Jenn's testimony that she drove Jay around Baltimore picking up shovels from dumpsters, taking to other dumpsters to discard the clothes he was wearing on the day of Hae's murder) in order for him to appear in an almost ghost like fashion those two days.
I've read that Jay's possible motive was because Hae was going to confront him on his cheating Stephanie with other girls. Hae could have called Adnan's cell that afternoon (see
here for phone logs to and from Adnans cell) at 2:36pm and got Jay on the end of the line.
Jay could have easily have asked Hae to meet him right there and then to discuss his philandering ways at a secluded spot and carried out the murder.
Everything that comes out of Jay's mouth with regard to Adnan, I think that that is in fact him and his actions. I think in his 'story' of lies he therefore needs and did have an accomplice - that cannot be him as he is Adnan in the story he describes. I have to think his accomplice is Jenn, the Detective's daughter from another County. (See excessive calls to and from her on day of murder)
I also have to think this is why the investigating detectives focused entirely on Adnan and believed what Jay and Jenn told them unconditionally, despite the admitted lies and inconsistencies.
I have so so much more thoughts on the whole matter, but will stop at that for now.