I Found Out My "friend" Is Abusing Children [california]

Location: San Francisco, California

About 3 months ago I (M24) made a bunch of quick friends through a shared activity. The guy who introduced me to the others (we'll call "Sam" M27) quickly became a close friend. He and I would frequently hang out with his girlfriend (who will become relevant, let's call her "Emma" F24) and other friend ("Sue" F25, who is actually Sam's ex-girlfriend).

Two weeks ago, Sue told me that Sam is a self-described "ephebophile" (an adult attracted to teenagers), but doesn't act on it. Which is something I have compassion for as long as it isn't acted upon.

Two days ago, Sam and Emma broke up. I called Sam and told him that we should get drunk about it. The next day, he and I went bar crawling and eventually went back to my place to hang out. At my house he asked if he could tell me something really personal. I considered him a close friend that I was consoling so of course I said yes. He told me that he "likes younger girls". I told him that Sue had mentioned something to me about him liking teenagers. He said "no, I prefer them younger". He shared with me that he was sexually abused as a child and has always found young children, ages 4-12, attractive.

Now Sam is a preschool teacher and I told him right away that he needs to find a new job. He then told me all these reasons for why it's actually the best job for him. Bunch of BS. He then told me that he has molested a lot of children, but never "used his penis" only "touched them under their pants". At this point I figured it was in the best interest of the children for me to create an environment where Sam felt like he could tell me everything. I asked him when was the last time he did this and he said yesterday. I asked if he thought he would be able to stop and he told me that there was a 0% chance he wouldn't do it the next time he goes to work.

Eventually we went to sleep. I let him crash at my house. He left this morning and after I finished work I met up with Emma. Sam had told me that he tried telling this to Emma when they were dating, but he ended up lying and said that he just had "Pedophile OCD" (an obsessive compulsive thought pattern where someone worries they might be a pedophile). I shared what I had learned with Emma and we are trying to figure out how to report him.

I learned that Sam is very good at covering his tracks online whenever he views CSAM and I really have no evidence that could convict him. I've talked with a number of people in his life and they confirmed that what I had heard is basically all true as far as they know.

I was planning to try and meet up with him again to secretly record our conversation with the hopes that he might reveal something prosecutable, but then I discovered that California is a two party consent state when it comes to recording conversations. I am really at a loss. I think that maybe I can try to find the families that he babysits for or the parents of the children at his preschool/the preschool itself and let them know what I know. But I am really worried that nothing will happen if I report him and he will continue molesting children.

TL;DR: my "friend", who is a preschool teacher, admitted to molesting dozens of children with no intention of stopping and I do not believe anything will happen if I report him, but he needs to be reported.