I
Yes, he did, and the FBI searched that van where it was situated in the Laundrie's driveway, No one else drove back with him, he stole it, and used it and used Gabby's credit cards ( Deceased Gabby, a crime in itself, using a dead persons credit card) to finance his trip home. ( Brian was a thief, and a murderer, one usually goes along with the other )
No one believes the Laundries didn't know that Gabby was dead. No one. Not in the USA< not in the UK, not in Canada not in AU< no one . It defies commonsense that they did not know and people will judge it on that ground alone, 'Does this make sense??" ...
This being a civil matter, it will be weighed up on the preponderance of the evidence, and the judge will ask himself, 'what would a normal person think and do in this cicumstance?'......
And the answer to that, everyone knows. E.V.E.R.Y.O.N.E.
Lots of fairy stories abound about Brian renting a car, to drive back, the van being left in Wyoming, these are not true. I don't know why these fairy stories are told.