Awful

He wasn't <i>that</I> random, really. You see him walk right passed Beth without even so much as acknowledge her at the beginning, which made him a suspect immediately in my mind. And I'll have to watch the scene again, but I'm pretty sure he was a cook at the diner in the scene where Liam finishes eating and leave his money on the counter. I remember the cook was eyeing Ryan up and thought it looked awfully like the weird valedictorian. Probably was, given the ending.

The only reason why I wouldn't have pegged him being the killer is because he just wasn't huge character in the film, but otherwise he should've been on any viewer's radar enough so for it not to be completely random.