A man accused of murdering Auckland pensioner Herbert Bradley in his apartment says the death was a tragic accident and his actions were justifiable self-defence after the 70-year-old lunged at him with a knife.

It can now be revealed the woman with whom Sergio Frederico Williams was living at the time, originally charged with murder, has agreed to co-operate with police and is set to be the star witness at his murder trial this week.

Williams, 36, has pleaded not guilty to murdering Bradley by stabbing him in the neck at his Upper Queen St apartment beside the Symonds St cemetery on August 23 last year.

His trial before Justice Jane Anderson and a jury of six men and six women began on Monday in the Auckland High Court.

The Crown case is that Williams was already ill-tempered after a fight with Sophie Rutland, a woman who had come to live with them some weeks earlier, when Bradley asked him to move out of the central Auckland apartment.

Sensing his flatmate’s increasing agitation, Bradley had grabbed a knife.

Then a chaotic struggle ensued, culminating in Williams plunging the blade into the 70-year-old’s neck all the way up to the hilt, said Crown prosecutor Rebekah Thompson in her opening address to the jury.

Bradley was no match for a much fitter and younger man literally half his age, Thompson said. She argued he used force far beyond what could be considered reasonable for self-defence in the circumstances.

Sarah Hames, representing Williams alongside Lorraine Smith and Philip Hamlin, said the death was a tragic accident.

Hames said Williams was defending himself from Bradley, who had lunged at him with a knife, and he had the cut on his hand to prove it.

“Both men were holding the knife at the same time when that knife went into Mr Bradley’s neck,” Hames said.

Hames argued her client’s actions amounted to an entirely reasonable level of self-defence. She urged the jury to ask themselves who was the aggressor.

“Who took the knife to the fight?”

Sergio Williams on the first day of his trial on the Auckland High Court on November 11, 2024. He has pleaded not guilty to murdering Herbert Bradley on August 23 last year. Photo / Michael Craig

Williams was originally charged alongside Rutland, 27, who had come up from the South Island to live with him some weeks earlier after the pair met on Facebook.

But it can now be reported her murder charge was dropped earlier this year when, after months in prison, she agreed to co-operate with police.

On Monday afternoon, following the opening statements from the Crown and defence, the jury watched a video of her interview with the officer in charge of the case, Detective Sergeant Ewen Settle.

Thompson, laying out the background to the Crown’s case in her opening, said Bradley had lived in the two bedroom Upper Queen St apartment since mid-2022. It was his daughter’s apartment initially but she moved out after Williams moved in.

He found it painful to walk and could be seen in CCTV footage moving with a pronounced limp, she said, while he was also starting to experience some cognitive decline.

Bradley had met Williams through an old friend called Bruce who repaired cars at his home in Portage Rd, New Lynn. William’s had turned up to Bruce’s place in West Auckland because his car had broken down.

Bradley ended up towing Williams’ car to another mechanics. The pair came to an arrangement where Williams would stay at Bradley’s apartment.

It was only meant to be for a few days while his car was being fixed, but turned into a weeks’ long stay, and his daughter Claire moved out, Thompson said.

Around the same time Williams had connected with Rutland, who was then living in the South Island, via Facebook.

They chatted for a while and had a few video calls before it was agreed Rutland would move up to Auckland to stay with him in Bradley’s apartment.

The trio lived together for a few weeks as flatmates, Williams and Rutland in one bedroom and Bradley in the other, Thompson said.

On the evening of August 22, Williams and Rutland had been at a gathering with some of his friends. Thompson said he had become annoyed at Rutland, who he felt was “playing up” or “acting flirtatiously” with one of his friends.

The argument continued after they returned home, and did not resolve before they went to sleep.

Late the following morning, Williams had come out of the bathroom following a shower to find Bradley and Rutland sitting together on the couch, having coffee, chatting and joking around, Thompson said.

Police were called to the Upper Queen St apartment complex on August 23 last year after Herbert Bradley suffered fatal stab wounds in his apartment. Photo / Raphael Franks

Williams became wound up and angry and went back to the bathroom. Bradley had grabbed a knife and hidden it behind his back so the other man couldn’t see it, the prosecutor said.

The pensioner then said to him “you’ve got to go, you’ve been here long enough, you’ve got to go,” according to the Crown’s version of events.

The argument continued, with Bradley repeatedly telling Williams he needed to leave, to finally “f*** off”.

Bradley asked him to go to the building manager’s office with him but Williams replied that he didn’t want to go anywhere on camera with him, Thompson said. Williams also began listing everything he’d done for Bradley, including helping him get painkillers and coffee.

At some point Bradley had gone outside to the balcony to cool off and Williams had started in on Rutland, the Crown claims, asking her to go into the bedroom.

Rutland refused and Bradley came back inside from the balcony, presented the knife and told Williams to leave the woman alone.

Williams picked up a bar stool and smacked him in the jaw before Bradley moved towards him with the knife, Thompson said. Williams then grabbed the knife and bent it backwards, she said.

The two men struggled over the knife before Williams managed to wrest control away from Bradley and plunge the blade into his neck, leaving a wound nearly 10cm deep, according to the Crown’s pathologist.

Police in the carpark of the Upper Queen St apartment complex shortly after Bradley's death.

Bradley stumbled out of the apartment and went down towards the office of the building manager on the ground floor. He was captured on CCTV approaching the manager’s door before collapsing.

Meanwhile, Rutland and Williams had packed up their effects and left the apartment, stepping over Bradley’s body in a hallway. Thompson said Rutland would later say she wanted to stop to help Bradley but realised he was already dead.

They went to Williams’ van and on the way Rutland asked a couple of construction workers for a smoke. Police arrived, found the pair in his van and arrested them.

Bradley was in a critical condition when paramedics arrived. He died on his way to hospital.

The trial continues on Tuesday.

George Block is an Auckland-based reporter with a focus on police, the courts, prisons and defence. He joined the Herald in 2022 and has previously worked at Stuff in Auckland and the Otago Daily Times in Dunedin.