Who said anything about Kevin being antisocial? I got the opposite impression -- that he was always involved in things. High school being what it is, I doubt he was considered a "cool kid." However, if you look at that Facebook memorial, it becomes obvious -- even if Kevin was a bit of a nerd or something, he was a very well-liked and well-regarded nerd. (Incidentally, in my own household, 'nerd' has an almost universally positive connotation. My 13-year-old stepdaughter wears the "nerd" badge with great pride.)
I've even learned the name of one person who has been questioned by police, and it was a youth, an acquaintance of Kevin's, and a young man who might seem more classically "antisocial" -- withdrawn, at the very least. Incidentally, until there's an arrest, I will not tell the name or publish it.
I'm all but convinced that what soccermom wrote above was the case: "we are looking for a juvenile. Someone that Kevin went to MTHS with, someone that wasn't "supposed" to commit a murder like this. Someone who didn't realize that Maggie was in the house."
Not a stranger, but someone who knew that neighborhood pretty well, too. I believe it was someone who lived close enough to sneak over to the Haineses by bicycle or car, park either out of the way, commit the murders, and still get back home within an hour or so. That means the killer probably lives within a 3-5 mile radius of the Haines residence.
This killer had a big hole knocked out of his life at some formative point, and it's never been filled. He's developed into a sociopath, he can't empathize with others, but he's probably learned to fake it pretty well. He may have run under the radar until now by being kind of introverted, the sort of kid who doesn't reveal too much about himself, ever. He has violent fantasies, and he's slaked a need for violence with video games and movies. At one time, this person was probably pretty close to Kevin.
I'm worried that this person's own family may be in danger, frankly.
Steve/Mr. A