Nation Expert at Derek Chauvin trial testifies that George Floyd suffocated because officers restrained him facedown and handcuffed April 8, 2021N'dea Yancey-Bragg, Tami Abdollah and Kevin McCoy, USA TODAYComments Off on Expert at Derek Chauvin trial testifies that George Floyd suffocated because officers restrained him facedown and handcuffed Dr. Martin Tobin testified Thursday in the murder trial of former Minneapolis police officer Derek Chauvin, charged in George Floyd's death.