Is this a mental illness? ?

A few days ago I met one of my cousin's friend. She looked like an average teen girl but she's kind of weird. I went to her house and everything was good until I went in her room. She has dead animals like birds, rats, lizards, and paws hanging from her ceiling and some in her closet. She has printed pictures all over her room of gore and necrophilia. I went on her laptop and when she left the room I looked in her pictures and saw nothing but gore and a lot of necrophilia. She also had saved videos of people killing others or people committing suicide. She also had saved a few suicide notes (not sure if she wrote them) and some other crap in a different language. She's really quite but she's also nice. She told me her parents died when she was 6 years old (not sure of what.) Is this some type of disorder or illness?