They were actually in the Trooper not the Dodge as would be expected.
Sorry for not being clear.
That is my whole point.
The seats WERE in the Dodge that day.
The murderer decided to take the Trooper to the border to fake Mexico. So they took the seats from the Dodge, and other miscellaneous kid stuff, and medicine and put it in the trooper to make it look like a trip.
My theory
