In the realm of wild speculation, but it takes just a moment to do something like that if you are young and fit enough. Me? Ah, that's another matter...with my cane on a bad day, and the slope in the driveway...no chance, but...a younger person, potentially, could accomplish this.
Not everyone locks the door that goes from garage to house, and this would be easy if that were the case. Or, of course, if there was access to NG's keys.
Just opinions formed while scrubbing dishes. Not fact or firm assertion.