A man on trial for killing a suspected thief has told a jury he was performing a citizen’s arrest and thought the man was faking it when he told him he could not breathe. Nathan Smith, a 38-year-old carer, said he had no intention of hurting Craig Wiltshire, 43, but simply wanted to detain him until the police arrived. He denies manslaughter. Smith pounced on Wiltshire in the early hours of 20 November 2019, pinning him to the ground for 12 minutes and kneeling on his back for nine of them. The jury at Bristol crown court has seen CCTV footage of the incident in which Wiltshire can be heard telling Smith: “I can’t breathe” but his captor replied: “I don’t give a fuck.” Wiltshire died two weeks later, a postmortem giving the cause of death as cardiorespiratory arrest and subsequent brain damage. The prosecution has alleged Smith used unlawful force on Wiltshire and wanted to punish him for crimes he believed he had committed in the neighbourhood. Giving evidence on Friday, Smith said he acted after houses, cars and sheds were broken into, leaving the community feeling worried and frightened. The incident happened when Smith spotted Wiltshire in the area. He told the jury: “I was just going to detain him and allow the police to get there. I pulled him off the bike and held him to the floor so he could not escape. “I was expecting the police to come and take him. The police station is [nearby] so I thought they would be there in a couple of minutes. I had no intention to cause any harm. “He was fighting back. I did not think him saying ‘I can’t breathe’ was genuine – I thought he was trying to get me to let him up so he could escape or attack me. It never went through my mind he couldn’t breathe.” As he waited for the police, Smith said he was fearful. “I was panicking the police were not coming and was just focusing on not letting Mr Wiltshire up. I thought if he got up he would hurt me, hurt one of the other residents or escape. “I was concerned he had a tool or weapon on him and did not want him to go into his pocket. I was just focused on detaining him and thinking I just hope the police hurry up.” After three police officers arrived, it became obvious that Wiltshire was unresponsive. Smith added: “I could not believe it. I felt confused and I was sick. I was very upset and distressed. At no time did I mean any harm to this male – I was simply making a citizen’s arrest.” The defendant said that since the incident in 2019 he had not been the same person. “I am on antidepressants. I used to be quite a happy person but now I just feel mostly sad.” On Thursday, Prof Jason Payne-James, a forensic physician and a leading expert on restraint techniques, said he believed the force used was “reasonable”. He argued that while police and prison officers would have known detaining someone in a prone position could lead to positional asphyxia, an untrained person would not have realised this. Payne-James said he believed “a perfect storm” of conditions and factors contributed to Wiltshire’s death including his small build, an existing heart condition, the presence of the heroin substitute methadone and the sedative diazepam in his bloodstream and the fact that he was struggling. But cross-examined by prosecutor James Ward, Payne-James said it was likely that Wiltshire would have survived if Smith had sat him up when he said he could not breathe four minutes into the restraint. The jury has been told to assume that Wiltshire was the man suspected of committing crimes in the neighbourhood over the previous weeks. The trial continues.