I know two people that have had vehicles stolen this very same way. DON'T WALK OFF AND LEAVE YOUR VEHICLE RUNNING WHILE YOUR "JUST GONE FOR A SECOND"!
I always have an extra key in the truck or in my pocket. If I do have/want to leave it running, I lock it up.But but but officer.....I just ran inside to get a coffee and it is cold so I left my car running.........Idiot.
Edit......yes. Lock the doors. Junior can let dad back in.