Nathan Matthews, stepbrother of Becky Watts, told police he did not like her as she was "rude" to his mother, a court heard.
Becky, 16, was allegedly murdered in her bedroom in Crown Hill, Bristol, by Nathan Matthews, 28, and his girlfriend Shauna Hoare, 21.
They are accused of targeting Becky in a sexually motivated kidnap plot on February 19 this year, culminating in her death.
Her dismembered body was discovered in a garden shed in Barton Court – 80 metres from their property – by police on March 3.
Former TA soldier Matthews admits killing Becky, dismembering her in his bath and moving her remains to the shed.
In an interview to police on February 28, played to the jury at Bristol Crown Court, Matthews admitted he did not like Becky.
"I don’t particularly talk to her but obviously I don’t particularly like her because obviously she has her moments," he said.
"We never actually had a proper argument or anything like that. I think one time I was shouting at Shauna and I might have shouted at Becky as well.
"The way she speaks to my mum or when she leaves clothes on the floor my mum could trip up on – she is self centred in a sense.
"Sometimes she will be rude or whatever or demanding."
Matthews said he chatted to Becky about her x-box, laptop and phone, her father Darren Galsworthy and downloading films.
Court artist sketch by Elizabeth Cook of (left to right back row) Nathan Matthews, two dock officers, Shauna Hoare (front row left to right) dock officer, James Ireland, dock officer and Donovan Demetrius at Bristol Crown Court where they are on trial in connection with the murder of Becky Watts
He admitted teasing Becky, who he said had a "mother daughter" relationship with his mother, Anjie Galsworthy.
"It was something like a dig or a joke or take the piss out of her," he said.
"She would say something and just if there was an opportunity to take a chance, like her nose being big or like her having a beard.
"She could laugh or say something back to me or she would shrug it off or say ‘Anjie, Nathan’s being mean’."
Matthews claimed Becky used her anorexia to secure lifts and planned to claim "benefit money".
"Obviously I don’t mean to be nasty, the anorexia thing, I know she started eating less but I don’t believe it is a condition," Matthews said.
"I know she passed out or fainted and I think they went to hospital and they were on about keeping her locked up and they said this to Becky.
"The next minute she was stuffing her face with cereal bars and packets of crisps. True anorexia you feel sick when you eat, you don’t go ‘I fancy a pizza with all them crisps’."
Matthews said Becky was moved to a different school because of the condition and was driven there by taxi in case she fainted on a bus.
"She was feeling more special by it," he added. "My mum was like ‘it stops now because you are back to the normal weight’.
"Becky wasn’t happy of the fact that it stopped."
Matthews, of Hazelbury Drive, Warmley, South Gloucestershire denies murder and conspiracy to kidnap.
He admits killing Becky, perverting the course of justice, preventing 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.
Donovan Demetrius, 29, of Marsh Lane, Redfield, Bristol, and James Ireland, 23, of Richmond Villas, Avonmouth, each deny a charge of assisting an offender.
Karl Demetrius, 29, and his partner Jaydene Parsons, 23, both of Barton Court, Bristol, have pleaded guilty to assisting an offender after Becky’s body parts were found in their shed.
Becky Watts
Detective Constable Russell Saunders arrested Hoare at her mother’s home in Wilton Close, Southmead, on February 28.
"I explained I had something to tell her that she may find upsetting but I needed her to listen carefully to what I said as it was important," he told the court.
"I said ‘I am arresting you on suspicion of the kidnap of Rebecca Watts, Rebecca was last seen at her home on February 19 and stopped communicating at 11am.
"’You were at the house at the time she stopped communicating. We also have investigative material that links you to the offence’.
"I gave her the caution. Hoare didn’t reply. I noticed Hoare had tears forming in her eyes. She didn’t cry openly. She just stood, compliantly waiting."
The officer conducted an urgent interview with Hoare in an attempt to locate Becky.
She answered "no" or "I don’t know how to, no" to questions about Becky’s location, her safety and how to help officers find her.
Mr Saunders said he had seen Matthews when he entered the semi-detached property at 3.20pm.
"Matthews was playing a video game and didn’t acknowledge us as we came in," he added.
Detective Constable Rob Dolan arrested Matthews and also asked the same questions to him. To each question, Matthews replied: "no comment", the court heard.
Matthews’ vehicle, a black Vauxhall Zafira, was later seized by police.
Source: http://www.liverpoolecho.co.uk/