A few thoughts:

• Local Police station visit request every 911 call or police report involving the address (and the renters by name if you know it)

• Background check renters in the broadest sense....like arrests.org and state court case websites. If they are actual criminals they will likely have a few of these cases and mug shots.

• Pictures from the police raids. If 10 cop cars show up, take pics. Get pics neighbors took or from social media.

• Present reports/pics to the property management co (if they are local) with other neighbors in tow and let them know you respect the law and expect them to as well. No need for threats - the implication of the evidence and your complaint is that if they don't take action there are other avenues (like going to the press which wouldn't matter much likely but if it's a college town or resort town sometimes they have active city councils)