Leslie Lothstein has seen them all: priests sexually active with adult men, others with adult women, others with adolescents, others with children. By his own count, Dr. Lothstein, a psychologist at the Institute of Living, in Hartford, has treated about 300 Roman Catholic priests, not only those with sexual problems, but also those with alcoholism, depression and other mental illnesses.

He has written widely on the topics of pedophilia and ephebophilia, or sexual interest in adolescents. And, when interviewed in his office last month, he was not at all surprised by the continuing revelations about sexual abuse by priests in the Catholic Church.

“I had predicted 15 years ago that this would go up to the pope,” Dr. Lothstein said.

He unwittingly found himself in the news almost 10 years ago, when it was reported that the Catholic Church had sent priests to the Institute of Living for treatment without always telling the doctors the full details of the priests’ transgressions. (One of those priests was the superpredator John Geoghan, whom Dr. Lothstein treated.) What’s more, the Catholic hierarchy often ignored the institute’s recommendations about the priests’ fitness for service.

“I found that they rarely followed our recommendations,” Dr. Lothstein told The Hartford Courant in 2002. “They would put them back into work where they still had access to vulnerable populations.”