Let people be. Why are you meddling?~
Don't go calling people psychs just cause they murder racoons with a chainsaw and throw rat poison into others' food. It's called "having fun". Damn lynch crowd.
Doesnt sound like she Needs any help
According to statistics 1/25 people is a sociopath or a psychopath, so everyone talks to them. It's normal wanting to understand something that's different from regular people, they are indeed very interesting to study. It's one thing wanting knowledge, which is cool, it's totally different wanting to entwine her life with one of them. I'm not saying it's good or bad, cause I myself have no experience with that, but it's definitely dangerous. If she understands the dangers and still wants to do whatever it is she wants to do, then it's her life. Thats all.
Ask her directly :)