From Murder to a Cathedral — John Creasey

Commander George Gideon of Scotland Yard is working on an intriguing case involving a mysterious man who is known to photograph young girls in the nude and the girls then vanish. He is also attempting to deal with serious internal problems at the Yard when yet another case comes in. There have been several cases of vandalism in major churches and cathedrals, and an anonymous caller has reported a thief in one church. It doesn't take long for Gideon to work out that the churches are threatened with far more than theft and vandalism.