The Scientology Murders: A Dead Detective Novel (Dead Detective Mysteries)

A 2017 police procedural novel by William Heffernan, about the Church of Scientology.
Clearwater, Florida, is the spiritual center of Scientology. A senior church leader there employs a young man who will stop at nothing to make sure the church's rules are followed - including mass murder. The cops know who is doing the killings, but are powerless to catch the murderer because the Scientology hierarchy is protecting him.
The detectives are stonewalled at every turn. Harry Doyle gets pulled into the case when his adoptive father is shot while trying to rescue a young woman from Scientology. As the bodies pile up, the Clearwater police become more desperate. When the Scientologists move the killer to Alaska, Harry Doyle and his partner follow . . .

https://www.amazon.com/Scientology-Murders-Dead-Detective-Novel/dp/1617755362/