When police asked Westley Allan Dodd why he killed children, he didn’t answer clearly, just said "I’ve thought a lot about it" then, he gave a declaration about how he started with his sexual deviation. This declaration was written in his journal titled "How it started" long before he was captured:
How it started
“ 1970 (…) John was a month older than I, and Mike about a month younger. The three of us were in John’s room getting ready to go swimming in a 1-foot deep pool he had. John and Mike wanted me to watch something.
They both pulled down their swim trunks, then touched their penises together. I don’t remember what was said, but I ended up doing it with Johnny (…) So, I had, at age 9, had one sexual experience with two nine- year-old boys, and one sexual experience while alone.”