Becky Watts
Becky Watts went missing on 19 February Facebook

The stepbrother of Becky Watts broke down in tears while describing his plan to police to make the 16-year-old "more appreciative of life". In the 11-minute video shown to jurors at Bristol Crown Court on 22 October, 28-year-old Nathan Matthews said he wanted to "scare" Watts so that she would not be "self centered".

During the course of the clip, Matthews sobbed, wrung his hands and buried his head in his hands and requested that officers refrain from reading a prepared statement in which he confessed to killing his stepsister.

Matthews was at first arrested for kidnapping the teenager, but he was subsequently rearrested for her murder after police found his bloody fingerprints on the doorframe of Watts' bedroom. After being accused of her murder, the delivery driver admitted to killing Watts in a written confession on 2 March. The court heard that as Matthews' statement was read out by his solicitor, in which he explained that he strangled Watts after his mask slipped, he plugged his ears with his fingers.

But in another interview a day later on 3 March, Matthews was pressed for details by officers and he said that he may have got the idea to kidnap Watts "from TV" and said: "I had a couple of dreams". In the video, Matthews said: "I came up with the idea to scare her.

"Like to try and basically make her more appreciative of life, like more appreciative of people, like she would be grateful that she had not been harmed," he said. "She would leave things out for my mum to trip over and talk to her like dirt on the floor.

"I thought if I was able to scare her, and she would not be harmed when she got back, she would have been scared and more appreciative of things," he added. "Obviously, stuck her in a suitcase; obviously, put tape around her mouth so she would not make a noise."

Matthews continued: "I would still have the mask on and scare her and say something along the lines of 'you have to start treating people better and not be a b***h and self centered and make a threat that this could happen again or worse'".

Throughout the video shown in court, Matthews, who was wearing a dark t-shirt could be seen staring fixedly at the floor. It is claimed that the teenager was suffocated in her bedroom during a botched kidnap attempt, before being stabbed 15 times and dismembered with a power saw. The court heard that Watts' body parts were "meticulously packaged" using clingfilm by Matthews and his 21-year-old girlfriend, Shauna Hoare.

The prosecution allege that neighbour Karl Demetrius, 29 and his colleague, James Ireland used a work van to transport her body parts. Watts' remains were found 11 days after her death behind a Bristol house belonging to Demetrius and his girlfriend, Jaydene Parsons, 23. Demetrius and Parsons admit assisting an offender, while his twin brother Donovan Demetrius (who lived in the same house) and Ireland deny the charge.

Matthews of Hazelbury Drive, Warmley, South Gloucestershire admits killing Becky Watts, preventing her burial, perverting the course of justice and possessing a stun-gun, but denies her murder and conspiring to abduct her. Hoare denies all charges against her. The trial continues.