I have never been able to buy into the assumption that RM went straight to the train depot from the house, especially once I saw that video of the parking problem early on. There would be more available parking up front after say 6 or 7 pm when commuters are coming home and most certainly on saturday when less people would be commuting. It would be useful to have someone give an account that is familiar with riding the train from Deer Park. But more importantly, why did he leave the house? Was it willingly and if not, why not communicate that he was leaving to IM as she was expecting him home around that time? Is there a correlation that he went home, went into the garage, left and the car being found with the trunk empty connected? And LOCKED to boot.
It may be possible that the person drove (possibly not RM) and parked the car there late saturday afternoon with the intention of returning to the vehicle later after a short commute on the train. But once returned.....