The serial killer daughter

Willa Petrova-Bennett was a child, when her father killed 50 women over the course of 10 years. His nickname suggests their deaths were very brutal and bloody. He was extremely protective of his daughter and was terrified of letting her out of the house because he knew there were more men like him outside. He tried very hard to be a good father and would give her all the the things she wanted, though he refused to have any pets and technology in the house because he knew he couldn't control his homicidal urges around pets and because technology was mostly not a good habit for kids.

In the end, he was arrested by Gideon, Rossi and Hotch. He would later say it was the best day of his life as it meant he no longer had to hide and wouldn't hurt anyone else. Because of that statement, it is possible that his killings, or at least a portion of it, were acted out of compulsion. He is currently in prison, since North Carolina doesn't have capital punishment, and is very likely serving a life sentence with no possibility of parole. He sometimes writes to Willa and she writes back to him because his her father and she love him no matter what since he practically raise her and was the best father any girl could ask for though she change last name to her mothers maiden name.