cops wont do anything, they just take the report and file it. After the car gets dusted for prints, it'll be in a file and if there are any prints and it matches to the ones that are already in data, they will look at it a little more then file it again. IF they do catch the guy for another offence and run the prints and finds a match, then they would charge the person for all the other offences previously. Other than that,they just file it.

if you are doing investigation yourself, i would suggest that you approach the possible suspects like you are interested in buying some parts and dont care if it's stolen or not because "you are one of them" let them open up to you and if they do sell the parts that are stolen or you have proof that the parts they are selling you are either stolen from your ride or from another ride, i'd report it to the police and they will have detectives look into the report you gave them and their proac team will go out and do a buy or something and catch the theives red handed on a buy or when they do another hit on another car.

Tommy