Dusting for fingerprints.
I just watched The Lost Boys, which was about an hour nd forty mins. However on IMDB it is Through the Clouds parts one and two.
Anyway, Creegan goes to Hinks house and tells him that h won't be able to prove he was there. Yet he is walking around without any gloves or any other protective clothing. Also when he goes o kill Hinks, he is again not wearing anything to prevent leaving evidence of his being there. Now I'm not sure about DNA back in the late 90's. But I'm pretty sure they would have been able to dust for fingerprints and would have found that Creegan was in the house had they investigated if Hinks complained or after he was found dead.
That's pretty sloppy work for a police officer.