Teen 'stabbed mother 79 times'

A teenager in the US accused of stabbing her mother 79 times allegedly sent her an email saying 'you will pay' the day before the attack.

Court documents filed revealed the twist in the story of Isabella Guzman.

The Denver Post reports that Ms Guzman and her mother often fought, but the teenager had become "more threatening and disrespectful" toward Yun-Mi Hoy in recent days, according to her stepfather, Ryan Hoy.

Police were called to the house and told Ms Guzman she could be told to leave the home.

When they returned hours later they found Yun-Mi Hoy dead in an upstairs bathroom.

Ms Guzman, 18, was arrested after a 16-hour manhunt and was held on suspicion of first-degree murder.

According to court documents, Mr Hoy called police when he heard a thumping and his wife calling his name.

When he went back upstairs he allegedly saw Ms Guzman standing in a doorway holding a knife and his wife's body on the floor covered in blood.

ABC7 News Denver reported that Ms Guzman allegedly spat in her mother's face the day of the attack.

Mr Hoy reportedly told homicide detectives that having the teenager at the home had been a challenge.

The Denver Post reports that Ms Guzman's mother had sent her to live with her biological father when she was about seven because her behaviour had become so difficult.

But Guzman's aunt, Melanie Guzman, said she saw a typical teenager when she visited the family a few months ago. Guzman could get angry, but violence seemed outside her character. Her mother spoiled her, she said.