Paramedics and George Floyd's girlfriend give evidence in Chauvin murder trial

Two first-responder paramedics and Courteney Ross appeared in court on Thursday

Paramedics who treated George Floyd said he was not breathing and had no pulse when they arrived at the scene of his arrest last May in evidence given on Thursday at the murder trial of former policeman Derek Chauvin.

"In lay terms, I thought he was dead," Derek Smith, one of the paramedics, told the jury.

By the time Mr Smith arrived, Mr Chauvin, who is white, had been pressing his knee into the neck of the handcuffed Floyd, 46, a black man, for about nine minutes, a scene that ignited global protests against police brutality.

Floyd's girlfriend smiled through tears as she told a jury how they first met when he offered to pray with her, less than three years before his arrest, and described how they both struggled with opioid addiction.

Courteney Ross, 45, was the first person who personally knew Floyd to give evidence in the trial.

"It's a classic story of how many people get addicted to opioids," Ms Ross, who wore a heart-shaped brooch on her black jacket, told the jury. "We both suffered from chronic pain: mine was in my neck, his was in his back."

Mr Chauvin pleaded not guilty to murder and manslaughter charges. In a central dispute of the trial, his lawyers argued that Floyd's death, ruled a homicide at the hands of police, was really an overdose caused by the fentanyl found in his blood at the autopsy.

Prosecutors from the Minnesota attorney general's office told the jury they will hear evidence to contradict this, including Ms Ross's evidence about his drug tolerance, and that Floyd's drug use is irrelevant to the charges against Mr Chauvin.

In this image from video, witness Courteney Ross answers questions in the trial of former Minneapolis police officer Derek Chauvin. AP

"It's one of my favourite stories to tell," Ms Ross said when asked by a prosecutor how she first met Floyd in August 2017 at a Salvation Army homeless shelter, where he worked as a security guard.

She was waiting in the lobby to see the father of her son, tired after closing up the coffee shop where she worked. Floyd approached her.

"Floyd has this great, deep, southern voice, raspy," she said, "and he was, like, 'Sis, you OK sis?'"

He sensed she felt alone and offered to pray with her.

"It was so sweet," she said, dabbing her eyes with a tissue. "At the time I had lost a lot of faith in God."

They had their first kiss in the lobby that night and, but for the occasional break after a lovers' quarrel, were together until his death, she said.

They took walks in the parks and around the lakes of Minneapolis, which was still new to the Texas-raised Floyd, and ate out a lot.

"He was a big man," she said, describing his daily weightlifting, "and it look a lot of energy to keep him going." She said he adored his mother, who died in 2018, and his two young daughters.

At times, they took prescribed painkillers. At other times, they illegally obtained opioids. Sometimes they shook the habit, sometimes they relapsed.

"Addiction, in my opinion, is a lifelong struggle," she said. "It's not something that comes and goes. It's something I'll deal with for ever."

Mr Chauvin's lead lawyer, Eric Nelson, asked Ms Ross many questions in cross-examination about how the couple obtained their drugs and about an episode where Floyd took himself to a hospital emergency room after what proved to be a non-fatal overdose.

She said she thought Floyd sometimes bought pills from Morries Hall, who was sitting in the car next to Floyd on the day of his death.

Mr Nelson has subpoenaed Mr Hall to give evidence when the defence presents its case and has told the jury that Mr Hall and a woman in the car would tell them that they saw Floyd swallow two pills before police arrived on May 25 and that he fell into a deep sleep.

Through a lawyer, Mr Hall said he would invoke his constitutional right against self-incrimination if called to give evidence, and asked Hennepin County District Judge Peter Cahill to quash the subpoena.

Ben Crump, a Floyd family lawyer, released a statement after Ms Ross gave evidence denouncing what he called "defence attempts to construct the narrative that George Floyd's cause of death was the fentanyl in his system".

"We want to remind the world who witnessed his death on video that George was walking, talking, laughing and breathing just fine before Derek Chauvin held his knee to George's neck, blocking his ability to breathe and extinguishing his life," Mr Crump said.

Floyd appeared to be not breathing and had no pulse when Seth Bravinder and Mr Smith of Hennepin Emergency Medical Services arrived in an ambulance outside Cup Foods, where Floyd was suspected of passing a fake $20 bill earlier in the evening.

They had to ask Mr Chauvin and other officers to move.

"They were still on top of him," Mr Bravinder told the jury.

His first thought was that some kind of struggle was going on, but it quickly became clear that Floyd was limp, and Mr Bravinder cradled Floyd's head as they transferred him to a gurney to avoid it hitting the road.

They stopped two blocks away to continue resuscitation efforts on Floyd. Mr Bravinder saw a flat line on the heart monitor.

"It's not a good sign," he said.

In cross-examination, Mr Bravinder told Mr Nelson he believed the emergency call he had been responding to included a note about the possible involvement of narcotics.

Floyd was declared dead at 9.25pm at a hospital in the city centre, just over an hour after he walked into Cup Foods.

Mr Chauvin, a 19-year veteran of the police force, faces up to 40 years in prison if convicted of the most serious charge – second-degree murder.

The other three former police officers involved in the arrest – Tou Thao, Thomas Lane, and J Alexander Kueng – will be tried separately later this year.