Which is the cause and which is the effect? He became a juvie judge because he's a pervert, or he looked into the abyss too many times dealing with cases? (those are not mutually exclusive. I suspect it's both)
My professional experience with this has been in healthcare. It involves usually physicians, with the occasional nurse, who is involved in inappropriate or sexual contact with juveniles, either their patients, or outside the patient pool. Based on my experience, and speaking with a number of psychiatrists/psychologists who treat the offenders, people with this paraphilia gravitate towards professions that bring them into contact with children. So I believe you will find a higher percentage of them working as teachers, Scoutmasters, pediatric physicians, juvenile justice, school bus drivers, nannies, healthcare workers, etc.
Years ago, there was a very well respected King County Superior Court Judge, Gary Little. I appeared in his court numerous times. It turns out that he had a habit of sexual contact with teenage males. In the late 80's, he shot himself in chambers after he learned an expose was about to be published in the Seattle papers.