George Floyd’s girlfriend has cried in court as she told the story of how they first met in 2017 at a Salvation Army shelter where Mr Floyd was a security guard.

Courteney Ross also recounted how they both struggled with opioid addiction on day four of former officer Derek Chauvin’s murder trial.

“Both Floyd and I, our story, it’s a classic story of how many people get addicted to opioids. We both suffered from chronic pain. Mine was in my neck and his was in his back,” Ms Ross said.

“We both had prescriptions. But after prescriptions that were filled and we got addicted and tried really hard to break that addiction many times.”

Prosecutors put the 45-year-old in the witness box as part of an effort to humanise Mr Floyd in front of the jury and portray him as more than a crime statistic, and also apparently explain his drug use to the jurors and perhaps get them to empathise with what he went through.

Chauvin, 45, is charged with murder and manslaughter, accused of killing Mr Floyd by kneeling on the 46-year-old black man’s neck for nine minutes, 29 seconds as he lay face down in handcuffs last May in Minneapolis.

The most serious charge against the now-fired white officer carries up to 40 years in prison.

The defence has argued that Chauvin did what he was trained to do and that Mr Floyd’s death was not caused by the officer’s knee but by Mr Floyd’s illegal drug use, underlying health conditions and the adrenaline flowing through his body.

A post-mortem examination found fentanyl and methamphetamine in his system.

Ms Ross began by telling how the two of them met.

“May I tell the story?” she asked. “It’s one of my favourite stories to tell.”

Ms Ross said she had gone to the shelter because her sons’ father was staying there.

She said she became upset because the father was not coming to the lobby to discuss their son’s birthday.

Mr Floyd came over to check on her.

“Floyd has this great Southern voice, raspy. He was like, ‘Sis, you OK, sis?’” Ms Ross recalled.

“I was tired. We’ve been through so much, my sons and I, and (for) this kind person just to come up and say, ‘Can I pray with you?’ … it was so sweet. At the time, I had lost a lot of faith in God.”

Minnesota is a rarity in explicitly permitting such “spark of life” testimony ahead of a verdict.

Defence lawyers often complain that such evidence allows prosecutors to play on jurors’ emotions.

The testimony came a day after prosecutors played extensive video footage: security camera footage of people joking around inside a convenience store, and bystander and police bodycam video of officers pulling Mr Floyd from his SUV at gunpoint and struggling to put him in a squad car before they put him on the ground.

It also showed Mr Floyd being loaded into an ambulance.

Chauvin, 45, who is white, is charged with murder and manslaughter, accused of killing the 46-year-old black man by kneeling on his neck for nine minutes, 29 seconds as he lay face down in handcuffs.

The most serious charge against the now-fired officer carries up to 40 years in prison.

Mr Floyd’s struggle with three police officers trying to arrest him, seen on bodycam video, included his panicky cries of “I’m sorry, I’m sorry” and “I’m claustrophobic!” as the officers tried to push Mr Floyd into the back of a police SUV.

At one point, Mr Floyd bucks forward, throwing his upper body out of the car.

Officers eventually give up, and Mr Floyd thanks them – and then is taken to the ground, face down and handcuffed.

Chauvin’s knee pins his neck, another officer’s knee holds his back and a third officer holds his legs, with the officers talking calmly about whether he might be on drugs.

“He wouldn’t get out of the car. He just wasn’t following instructions,” officer Thomas Lane was recorded saying.

Lane also asked twice if the officers should roll Mr Floyd on his side, and later said he thinks Mr Floyd is passing out.

Another officer checked Mr Floyd’s wrist for a pulse and said he could not find one.

The officers’ video was part of a mountain of footage and witness testimony on Wednesday showing how Mr Floyd’s alleged attempt to pass a counterfeit 20 dollar note at a neighbourhood market last May escalated into tragedy.

When Mr Floyd was finally taken away by paramedics, Charles McMillian, a 61-year-old bystander who recognised Chauvin from the neighbourhood, told the officer he did not respect what Chauvin had done.

“That’s one person’s opinion,” Chauvin could be heard responding.

“We gotta control this guy ’cause he’s a sizable guy… and it looks like he’s probably on something.”

Mr Floyd was 6ft 4in and 223lbs, according to the post-mortem examination, which also found fentanyl and methamphetamine in his system.

Chauvin’s lawyer said the officer is 5ft 9in and 140lbs.

Mr Floyd’s death, along with the harrowing bystander video of him gasping for breath as onlookers yelled at Chauvin to get off him, triggered sometimes violent protests around the world and a reckoning over racism and police brutality across the US

The defence has argued that Chauvin did what he was trained to do and that Mr Floyd’s death was not caused by the officer’s knee, as prosecutors contend, but by Mr Floyd’s illegal drug use, heart disease, high blood pressure and the adrenaline flowing through his body.

Events span out of control earlier that day soon after Mr Floyd allegedly handed a cashier at Cup Foods, 19-year-old Christopher Martin, a counterfeit note for a pack of cigarettes.

Mr Martin said he watched Mr Floyd’s arrest outside with “disbelief – and guilt”.

“If I would’ve just not taken the bill, this could’ve been avoided,” Mr Martin said, joining the burgeoning list of witnesses who expressed a sense of helplessness and lingering guilt over Mr Floyd’s death.