Part of the fun I have as president of my condo HOA was buying and helping install a security camera system. I also ended up being the only one in the building who knows how to access the videos the cameras take after everyone said they didn't want to know how to do this (the cameras were installed after someone drove into the overhang in front and someone else drove into the garage door - and neither party paid for the damages). We also put up 2 signs that say security camera in use in the garage.
A couple of weeks ago a new family moved into the building from another state. Our live in maintenance guy let me know about the mom of family parking their minivan in a far corner of the garage earlier this week (far away from their parking space, and in a part of the garage that is covered by 2 of the cameras), and that it was parked there for over an hour with the engine running. The mom moved up to the drivers seat as he tried to see in the back to see if anyone was in there (the minivan has tinted windows in the back, and he couldn't tell if anyone was inside it until he got next to it) and left shortly after that. The guy in the back was trying to hide as they left, and we're not sure if he is or isn't her husband.
My main worry is the potential CO accumulation that could result from the prolonged idling, but I'd also like to let her know about the security cameras in the garage. Assuming she's not too embarrassed by what's already happened (which I'm hoping isn't the case) and turns the engine off, what's a good way to point out their actions are being recorded if this happens again?