The reason why the Cops don't care is that vehicle break-ins is a low level priority for them, you are lucky they sent someone out to you. The best thing to do is as mentioned set up a sting car with some camera's. If the parking area is dark, I would contact the landlord and request he/she puts up some security lights. In a lot of states once a landlord has been made aware of problems, they have a responsibility to their tenants to try and remedy them.

I myself would sit up wait for the him to hit, making sure he is in the act before I gave him a good beating, while attempting to detain him for the police. You have a right(in most states) to defend your personal property, as long as you don't use unnecessary force.