If someone comes to your door claiming to be a law enforcement officer DO NOT OPEN THE DOOR. Ask them to slip a warrant under the door with your address on it. If they don’t have one, DO NOT open the door. Ask them for their credentials and write them down. Call their office to verify they are who they say they are. Write down their physical description. Use these forms.
If they have not parked in front of your house, you should be suspicious. Often, criminals who are trying to extort money from you park away from your house so you can’t write down their license plate number.