Justin Deryke says he was just trying to put his 7-year-old niece "out of her misery" when he killed her over the weekend.
Officials say autopsy results contradict his story. Deryke claims he was watching a movie with Willow Long over the weekend when she allegedly scratched his arm. He became angry and chased Willow out of the house. He says she fell into a brush pile and a branch stabbed her in the neck. That is when Deryke says he got a knife and stabbed the girl to death.
The autopsy shows Willow had defensive wounds on her hands and that casts doubt on Deryke's story.
Willow's 3-year-old brother has been taken into protective custody.