Christopher Martin was 19 and working the evening shift as a cashier at Cup Foods on May 25, 2020, when George Floyd paid for a pack of cigarettes with a blue-hued $20, setting off events that would change both of their lives.

Store policy dictated that employees must pay out of pocket if they accept a counterfeit bill. Martin decided he'd take the hit, but his manager told him to go talk to Floyd, sitting outside in a parked vehicle, and bring him back inside. But after two attempts, Martin said Floyd appeared "high" and didn't want to return to the store. A manager ordered a co-worker to call 911, Martin told a federal courtroom Tuesday morning.

Later Martin saw a crowd gathering outside. He stepped out of the store and saw an officer on top of Floyd.

"He just had his knee on his neck," Martin said.

Asked how Floyd looked, Martin told the court: "Dead."

Martin, now a 20-year-old college student studying business, recounted the events in the civil rights trial of three former Minneapolis police officers who were on scene that evening.

He was among the first witnesses to take the stand in a pattern that so far repeats testimony in last year's state trial for Derek Chauvin, the officer Martin saw on Floyd's neck. Chauvin was convicted of murder in April.

Martin said he used his cellphone to record the scene where Floyd died but quickly deleted the video because he didn't want to show it to anyone or even watch it again. He called his mom, who lived above Cup Foods, to warn her it wasn't safe to come downstairs.

The ex-officers' defense attorneys took turns questioning Martin. Among them, Tou Thao's attorney, Robert Paule, elicited that Martin met with nine attorneys in preparation for his testimony in Chauvin's state trial. He asked Martin whether he had told the prosecutors that Floyd was so high that he was unable to carry on a conversation inside the store.

Video is key to both sides

The day began with jurors watching Floyd's final moments from the perspective of one of the officers who helped restrain him.

That footage showed J. Alexander Kueng's body-worn camera fixed on the passenger-side rear tire of a squad car, as bystanders can be heard shouting from the sidewalk that Floyd is unresponsive.

"You think that's cool, bro?" said one man, Donald Williams. "You're a bum for that."

At one point, Kueng looked up and the camera showed Thao, his fellow officer, holding back a group of concerned bystanders on the sidewalk.

Videos are critical evidence for both sides, showing the perspective of the officers' cameras as their senior colleague, Chauvin, knelt on Floyd's neck for more than nine minutes.

Prosecutors say the officers allowed Floyd to die. The defense lawyers said their clients had limited information and relied on Chauvin's expertise, a perspective that jurors will weigh as they determine whether they had a duty to intervene.

The footage from Kueng's camera showed his perspective as he and his partner, Thomas Lane, approached Floyd in the vehicle outside Cup Foods. The confrontation was chaotic and loud from the beginning. The officers told Floyd to show his hands and then cuffed them behind his back as they said he wasn't following commands.

"When you're moving around like that, that makes us think way more is going on than we even know," one of the officers shouted.

Then Kueng and Lane struggled to push Floyd into the back of the squad car, as Floyd said he was scared and "claustrophobic." Floyd ended up pinned to the ground, pleading: "Mama, Mama, Mama." And then, "I can't breathe. Mama, I love you."

After a limp, nonresponsive Floyd was taken away in the ambulance, Kueng returned into Cup Foods. A clerk asked, "How's it going?"

Kueng responded, "Good. How about you? You still have that 20?"

Kueng asked the clerk what Floyd had purchased with the suspected counterfeit bill. The clerk said Floyd had bought cigarettes, and the video showed Kueng taking notes on a small pad in front of his chest.

Witnesses say officers could have done more

Charles McMillian also reprised his emotional testimony from Chauvin's trial.

The 61-year-old McMillian, a self-described "nosey" neighbor who saw the officers detaining Floyd and pulled over, was the first witness on the scene.

Prosecutors played videos in which McMillian can be heard telling Floyd to cooperate. On the stand, McMillian recalled telling Floyd to get in the back of the squad and make it easy on himself, saying, "You can't win."

"Once you get in handcuffs, you can't win," he testified.

As he did last year, McMillian became teary on the stand as he said: "I knew something bad was going to happen to Mr. Floyd … that he was going to die."

During cross-examination, the defense attorneys focused on how McMillian couldn't see the whole scene.

"Did you hear officer Lane say, 'I think he's passing out?'" asked Earl Gray, Lane's attorney.

"No, sir," replied McMillian.

"So, you didn't see officer Lane assisting the ER people?" Gray asked.

"No, sir," McMillian replied.

"So, your answer to the questions that you didn't see these police officers helping George Floyd at all isn't based on much?" Gray said.

Jena Scurry, a 911 dispatcher for Minneapolis, testified that the officers didn't report that Floyd was having trouble breathing. If they had, she could have sent "rescue" medical help from the fire department, which can get to a scene quicker than Hennepin County EMS.

"They can be almost anywhere within four minutes," she said.

Instead, the officers first requested an ambulance for a "mouth injury," calling it a "code 2," meaning not in need of "lights and sirens," she said.

Scurry said she "grew concerned" when she saw the officers on scene with Floyd for so long on a city surveillance camera, so she called and reported the odd behavior to a sergeant at the Third Precinct.

Testimony resumes Wednesday morning.