I'd bet money they are neighborhood kids/teenagers. Cigarettes and cokes? Most 'hard core' guys are gonna target stuff they can fence and get cash for.
Harbor freight has got a color camera with IR night vision for chump change:
http://www.harborfreight.com/weatherproof-color-security-camera-with-night-vision-95914.html
That is who we think it is to but none of them have kids that around that age. And im looking into motion detection lighting on the garage. Might even put a trail cam out there lol.