You were correct in filing a police report.
If you have a good relationship with the neighbor, then speak to him. Most likely, he won't admit to anything, and this will tip off the person that did it.
You have no recourse against the person you suspect had the guest that did it, even if they did admit to knowing the offender.
If you don't think the neighbor will give you the name (assuming it was his guest, and not another's who just parked in his spot, or someone in a completely different apt getting dropped off) then I would just not say anything and hope you see the vehicle again. Your other alternative is to ask the neighbor, and if you don't get some info, then post signs around the complex hoping to find a witness.
Either way, you won't get anything from the tenant, and will most likely have to take the offender to civil court if you do in fact find the vehicle. While the police most likely won't press charges against that person, they should give you their information to file a civil case.