I remember several insurgent weapons (two?) were lost or disappeared from from investigators custody, or a military vehicle, that investigators turned over for transport.
I can’t remember if those weapons were supposedly from the white vehicle or from one of the houses.
I remember that insurgent weapons went missing after the the ambush. I can’t remember for sure if it involved the white car.
At the time and for a while afterward, the incidents surrounding the IED blast and ambush weren’t considered out of the ordinary, so “evidence” wasn’t a thought.
Here’s a link to some of the Chessani testimony where the existence and then absence of weapons is explained...
http://warchronicle.com/DefendOurMarinesExclusive/ChessaniSpeaks-28July10.htm
Red will have more insight into this...