Derek Chauvin’s murder trial began Monday in a landmark moment for the nationwide reckoning on race sparked by George Floyd’s death, with prosecutors saying the former Minneapolis police officer killed Floyd “without regard” and the defense saying Chauvin’s use of force was necessary to restrain a man who overpowered him.

Behind a piece of plexiglass in a tightly fortified court, prosecutor Jerry Blackwell told the jury of six men and nine women, who include two alternates, that Floyd, a Black man, was defenseless and unarmed as he was writhing on the ground in pain while Chauvin, who is white, kneeled on Floyd’s neck and back for more than nine minutes on May 25, 2020.

“He put his knees upon his neck and his back, grinding and crushing him, until the very breath,” Blackwell said before playing the viral footage of Floyd’s death in the courtroom. “Until the very life was squeezed out of him.”

A masked Chauvin took notes in the courtroom as Blackwell told the jury the trial was not about every police officer or about policing in general. The prosecutor said police officers have difficult jobs, sometimes having to make life-or-death decisions in a split second. But, he said, “this case is not about split-second decision-making.”