If that's true, that's two different people, other than the parents, who lied to LE. PN and SB (surely she would have noticed PN still there for 4+ hours). I feel fairly confident that LE did not consider PN to be there all night in the early going in this case, due to their comments about him early on. That means to me the information given to them at that time (from interviews with parents/PN/SB) was that he was not there all night.
PN is not the only one to mention the drinking. What about Shane, the guy who visited the ladies for a period of time that night? He also said that although he didn't see them actually drinking, it was obvious that they had been?
BBM
I don't think he could have been there all night. SB and Shane would have told LE the truth about that I'm sure.