Becky Watts's stepmother has insisted she still loves her killer son and will visit him in prison in a quest for answers.
Anjie Galsworthy described her porn-obsessed son Nathan Matthews as a monster after he was convicted of brutally murdering his 16-year-old stepsister at Bristol Crown Court yesterday.
Matthews' long-term girlfriend, Shauna Hoare, was found guilty of manslaughter and trying to cover up the crime.
They are due to be sentenced tomorrow, along with Jaydene Parsons, 23, and Karl Demetrius, 30, who owned the shed where Becky's body parts were hidden. The pair admitted assisting an offender.
Mrs Galsworthy told ITV's Good Morning Britain (GMB): "I still love him, I just find it hard looking at the monster he's turned into.
"He's totally different from the child I brought up.
"I will ask him why - why this happened."
She and her husband Darren - Becky's father - trusted Matthews and Hoare and thought police had made a mistake when they accused the pair.
"When they arrested them we still said 'You've got it wrong'," Mr Galsworthy said.
"We trusted them and the betrayal hurts so much.
"We loved them - they were all our kids even if they had different DNA. It didn't make no difference. We loved them, they were our family."
Becky suffered more than 40 injuries as she fought for her life in her bedroom on February 19.
Matthews said he acted alone and that he only meant to scare Becky - not kill her. He later cut her body up in an effort to evade police, while members of both families searched for the missing schoolgirl.
The truth about what happened to Becky, who was suffocated by Matthews, may never be known.
Mr Galsworthy told GMB: "I feel like an empty husk of a man now.
"I feel like I've let my daughter down because every dad should be able to fight for his family but I wasn't given that choice ... they made sure I wasn't given that choice."
Becky's father told the BBC his home is "eerily quiet" without her, and said the teenager and Matthews were "like brother and sister".
"He was pretty good with her, to be honest," Mr Galsworthy said.
"He used to take her around all the adventure playgrounds.
"Ironically her first clear word was the word Nathan."
Becky's best friend, Courtney Bicker, said Matthews had a "morbid sense of humour" which frightened his young sibling.
She told Sky News: "She told me quite a few times that he had graphically described how he would kill her and she was quite scared of that, it was quite disturbing to her.
"She thought enough of it to make her scared of him."
Courtney described Becky as a "generous and very kind person" and a "funny girl" and said she has not come to terms with her death.
"Some days it's like it's not real and other days it all just comes crashing down," she added.