What if Billy didn't kill the little girl, Janice...

I think it was totally unrelated. I think the killer of the girl is not the same as Billy.

Out of interest, is the girl named in the movie? I probably missed it, but I don't remember her name being mentioned.

To answer the question, I always took it as 50/50 as to whether Billy killed her. I mean, it would make sense because he was going round murdering young women. But at the same time, I always liked the idea that it was the victim of a different crime that the police just happened to find when they were looking for Claire.

It's never explained either way. So I guess it's up to the viewer to decide whether the girl in the park was murdered by Billy or not. A lot of things in this film are left for the viewers to theorise about. (At one point, I got into wondering if the corpse they found in the park was of Agnes.)

Really, I took the search in the park more as a plot point to keep the police busy whilst Billy was going about his work. Otherwise, they'd have found Claire in the attic pretty quickly.

In this movie, anything is possible.