Okay. So this.
Mr. Lanza has a loose end called an ex wife and is paying
six figures annually for alimony.

Wife is a shooter, so is a bit dangerous.

Mr. Lanza calls in a favor among buds, and they make a deal.
Obama's assassins will get rid of ex wife and son,
if they can use it to publicize a mass shooting for gun control.

Obama's kill team moves in on the 13th, and kills mother and son,
(favor to Mr. Lanza) then drags the son's body to the
school and plants it, with dead mother's weapons.

School has probably not been locked up the night before,
someone paid off for that.

After daybreak, the kill team, still in the school,
starts shooting kids, or maybe not, or maybe just some
kids, and escape through woods.

One is accidentally snared by local cops not tipped to op,
and is released.

The OP, planned in 2010, has a rogue's gallery of actors
and observers who've bought tickets, stationed at the fire house.

Media chaos ensues.

Sounds about right. Just having a Sherlock Holmes
moment.