A California church deacon allegedly sexually abused numerous boys on religious mission trips under the guise of inspecting their genitals for “concerning” moles—helping protect the children, he told them, from the ravages of skin cancer.

The abuse dates back to at least 2009, according to a criminal complaint unsealed in Sacramento federal court upon his July 7 arrest and reported first by The Daily Beast.

Bradley Earl Reger, 67, “used his position of authority… to groom children and continually grope their naked genitals for his own sexual pleasure,” federal prosecutors said in a detention memo after Reger was taken into custody. Local police first received reports in 2003 of abuse by Reger, who “never seemed to run out of teenage boys whose genitals he could fondle under the guise of medical ‘exams,’” according to the memo.