But Tobin said where Chauvin had his knee after the five-minute mark would not make much of a difference, because at that point, Floyd had already experienced brain damage.
Chauvin attorney Eric Nelson has repeatedly shown the jury still images from the video that he said showed Chauvin’s knee was on Floyd’s shoulder blade. But nearly all of those images were captured more than five minutes into the ordeal, according to video time stamps.
Tobin explained to jurors what happens as the space in the airway narrows, saying breathing then becomes “enormously more difficult,” like “breathing through a drinking straw”.
Tobin testified that if the hypopharynx – the bottom part of the throat – becomes totally obstructed, it takes just seconds to reduce the level of oxygen to where it would result “in either a seizure or a heart attack”.
Prosecutors showed images of Floyd side by side, one with the front of his face pressed against the pavement and another with his head turned. Tobin said that when Floyd’s head was facedown, a ligament at the back of his neck would have protected his airway. But with his head turned, Chauvin’s weight would have compressed the hypopharynx.
The expert calculated that at times when Chauvin was in a near-vertical position, with his toes off the ground, half of Chauvin’s body weight – 41.5 kilograms – was directly on Floyd’s neck.
Tobin used simple language, with terms like “pump handle” and “bucket handle” to describe the act of breathing for jurors. At one point, he invited them to “examine your own necks, all of you in the jury right now” to better understand the effect of a knee on a person’s neck.
Most of the jurors felt their necks as Tobin instructed, though the judge later told them they didn’t have to do so.
Chauvin, 45, is charged with murder and manslaughter in Floyd’s death on May 25. Floyd was arrested outside a neighborhood market after being accused of trying to pass a counterfeit $20 bill. A panicky-sounding Floyd struggled and claimed to be claustrophobic as police tried to put him in a squad car, and they pinned him to the pavement.
Bystander video of Floyd crying that he couldn’t breathe as onlookers yelled at Chauvin to get off him sparked protests and scattered violence around the US.
Nelson has argued that the now-fired white officer “did exactly what he had been trained to do over his 19-year career,” and he has disputed that Chauvin’s actions were what killed Floyd. Fentanyl and methamphetamine were found in Floyd’s system.