"and it's going to be a young person, young 20s emotionally, but also because that's the age most likely statistically somebody's going to commit a crime like this." 
Actually, I think that you'll find that the younger the criminal who goes on such a killing spree, the more shots are fired in each encounter. Firing discipline (e.g. one shot = one kill) is not associated with the very young.
Moreover, this particular killer is strictly limiting her (oops, his) victims to one person per encounter, rather than taking in more than one target of opportunity.
That's two facts, not conjecture, that point towards strict training in this person's background.
I tend to agree. (course I know nothing about sniping or guns or such but the discipline aspect makes sense and doesn't sound like some young punk getting even with society...)
Actually, I think that you'll find that the younger the criminal who goes on such a killing spree, the more shots are fired in each encounter. Firing discipline (e.g. one shot = one kill) is not associated with the very young. Moreover, this particular killer is strictly limiting her (oops, his) victims to one person per encounter, rather than taking in more than one target of opportunity.
That's two facts, not conjecture, that point towards strict training in this person's background.
I agree on the discipline and the training. As for the age of the perp, I think we're all in the dark. These serial sniper attacks are completely unprecedented. There's no previous profile from which to speculate.
