Footage from a police interview with Becky Watts' stepborther, who is accused of murdering the Bristol teenager, has shown him describing his plan to "scare" her and “teach her a lesson” by kidnapping her wearing a disguise.
Nathan Matthews, 28, is seen breaking down and crying as he recounts "accidentally" killing Becky by strangling her when he “panicked”.
Jurors were shown the footage at Bristol Crown Court today, where Matthews and his girlfriend Shauna Hoare are standing trial for murder.
The video, provided by Avon and Somerset Constabulary, shows him breathing heavily with his head on the table as he was questioned.
After admitting killing Becky, he said he had only intended to frighten the 16-year-old and make her “more appreciative of life (and) other people”.
“I came up with the idea to scare her, to try and basically make her be grateful that, you know, she wasn’t harmed or anything like that,” the court heard him say in the interview.
“She’d leave things out on the floor for my mum to trip over and would say nasty comments and talk to her like dirt on the floor.
“And I thought that if I was able to scare her, and obviously her not harmed and be released…when she got back…she would have been scared and more appreciative of things, as people are.”
Matthews went on to detail his plan to put his stepsister in a suitcase after silencing her with tape, in the video played to the jury.
He continued: “I was thinking of a wooded area, or whatever, to take her out and obviously still have the mask on…and scare her and say something along the lines of ‘you’ve got to start treating people better and not be a b**** or self-centred, and like make a threat like or this could happen again or worse’.
“Something like that…I would have chucked away everything first and come back, and acted normal. Gone back to my mum’s and acted as normal.”
Matthews and Hoare, 21, were initially arrested on 28 February on suspicion of kidnapping Becky and were later detained on suspicion of her murder after blood was found on her bedroom doorframe.
Matthews, of Hazelbury Drive, Warmley, denies murder and conspiracy to kidnap but admits killing Becky, perverting the course of justice, preventing the burial of a corpse and possessing a prohibited weapon.
Hoare, of Cotton Mill Lane, Bristol, denies murder, conspiracy to kidnap, perverting the course of justice, preventing burial of a corpse and possessing a prohibited weapon.
Her boyfriend, a former Territorial Army soldier, told detectives he concealed his actions and absolved her of responsibility in a written statement.
The residents of the Barton Court property where Becky’s dismembered body parts were found, Karl Demetrius, 30, and his partner Jaydene Parsons, 23, admit assisting an offender.
Donovan Demetrius - Karl's twin brother - of Marsh Lane, Bristol, and James Ireland, 23, of Richmond Villas, Avonmouth - a work colleague of Karl's - deny the charge.
