A number of things that this kid did that raised my suspicions:
> Initially runs to a side door, spends 10 seconds there, despite it visibly having no post-box
> Runs to other door (used for burglary) and spends another 10 seconds there
> He is running to/from the house, yet pauses for so long at either door?
> When initially running towards the house, the kid is looking directly at the spot where the car is usually parked. It would be unnatural for someone to be looking in this direction, whilst running in a completely opposite direction
> The kids trainers are almost identical to one of the people who came and stole the car
> The kid turns up 30 minutes after we leave the house for an evening meal
> When we return from evening meal, me and my partner do not recall seeing any flyers through the letterbox
Some of the above may seem circumstantial, but it's been enough to make me (and the police) think he's related to the theft.