Irishman Martin Tobin, a pulmonary expert based in Illinois, testified on Thursday that George Floyd died from low oxygen to the brain, as he appeared at the Derek Chauvin murder trial in Minneapolis.
Professor Tobin, who is affiliated with Loyola University, took the witness stand on the ninth day of the high-profile trial.
Derek Chauvin, a former police officer who pressed his knee on Mr Floyd’s neck as he died in May last year, is facing charges of second-degree unintentional murder, third-degree murder and second-degree manslaughter. The 45-year-old denies the charges against him.
Under questioning by the prosecution, Mr Tobin said that a healthy person would have died from the same restraint exerted by Mr Chauvin on Mr Floyd. He said Mr Chauvin’s knee remained on the detained man’s neck for three minutes and twenty-seven seconds after he took his last breath. The knee also remained on the neck for two minutes and 44 seconds after the officers themselves found there was no pulse. He explained that the combination of Mr Chauvin’s use of handcuffs, and the placement of his left knee on Mr Floyd’s neck and right knee on his back, contributed to his death.
Mr Tobin outlined how Mr Floyd tried to lift himself at one point off the ground in an attempt to get air by pressing his knuckles against the ground and the police car’s tyre. He also pinpointed the exact moment on the widely-seen video of Mr Floyd’s death when the victim died.
The pulmonologist undermined a key argument of the defence in the trial - that Mr Floyd died from underlying health conditions or the presence of the drug fentanyl in his system rather than asphyxiation.
He said Mr Floyd’s respiratory rate suggested that fentanyl had no role in causing his death. He also pointed out that people who die of a fentanyl overdose enter a coma, but Mr Floyd did not.
Under questioning by defence lawyers, he also disagreed with the defence team’s argument that the lack of bruising on Mr Floyd’s neck showed that Mr Chauvin placed his knee on his upper shoulder rather than the victim’s neck. “Whenever I go to church I sit on a hard bench,” he said. “I don’t get bruising of my buttocks when I leave, so I wouldn’t expect anything in terms of that.”
Mr Tobin, who was born in Kilkenny, studied in University College Dublin. He appeared as a witness for the prosecution. He did not accept a fee to testify for the state, the court heard.
Following Mr Tobin’s testimony, Dr Daniel Isenschmid, a forensic toxicologist in Pennsylvania who performed the toxicology tests for Mr Floyd’s autopsy, took the stand on Thursday afternoon. He said that a “low amount” of fentanyl had been found in the victim’s system. He said this was not consistent with an overdose.
The testimony from medical experts is the latest phase in the trial which is coming to the end of its second week. Earlier this week, the court heard from use-of-force experts and other law enforcement officials, who were questioned on the appropriateness and legality of Mr Chauvin’s handling of Mr Floyd after he and other police officers detained him. On Wednesday, Minneapolis police chief Medaria Arradondo testified that Mr Chauvin had violated the agency’s policy on force during Mr Floyd’s arrest.
The death of Mr Floyd last year, which was filmed by a passer-by on his phone, sparked protests in America and across the world about racial injustice and the use of police force on African-American people.
The trial is expected to last for several weeks in total, with the defence due to call witnesses next week.
