What are the chances that a truck looking identical to the husbands would just happen to be in the field exactly during the time Venus disappeared, especially since it had four doors!
I would guess for every four door truck sold, at least 10,000 two door trucks are sold. They aren't that common and I am certain the fact that it had four doors stood out in the mind of the neighbor who saw it. I know I always thought, when I had four children to haul around and loved to go in the woods, "I wish I could afford the gas to drive one of those!"
So, in my opinion, the witness is credible and it absolutely had to be Doug's truck they saw.
As far as the two friends who are providing Doug with an alibi, we don't know if they are lying, or not. I sure hope it can be proven they are!
As far as charging and arresting Doug is concerned, the district attorney needs to be very cautious about not jumping the gun due to the fact Doug could exercise his rights to a speedy trial and ultimately be exonerated.
There is no proof Venus is dead. Until her body is found, don't expect any charges to be filed.
I am sure there is a lot of evidence to go over, including all the hard drives on the confiscated computers, checking the Internet browsing history, reading e-mails, reviewing phone records, etc. etc. etc.
If it can be proven by the tire mark impressions that it was in fact Doug's truck in that field, law enforcement can use that as a bargaining tool to attempt to get him to talk. Perhaps they will offer reduced charges if he reveals what he did with Venus.
SCENARIO: "Doug, we know your truck was in the field across from Venus's parent's home on the morning she disappeared because your tire treads exactly match the casts that were made. If you tell us what you did with Venus, we will not charge you with first degree murder, kidnapping, crossing state lines to commit a felony, etc. but only charge you with (insert charge)."
