BTK was a Cub Scout leader and used a false story as an alarm repairman to gain entry to one of his victim's houses.

Rader used an ADT hard-hat and a Southwestern Bell manual to pose as a technician for the telephone company.[117] Rader first gained entry into Wegerle's neighbor's house, and pretended to do telephone work, before leaving and knocking on Wegerle's door, doing so to make Wegerle less suspicious.

Fun fact: his son served on the naval base in New London at the same time as me. Not on the same submarine, but same waterfront a few piers down. Ran into him a few times.