Thao had opted to allow Hennepin County District Judge Peter Cahill decide whether he was guilty or not guilty, waiving his right to a trial by jury.
Derek Chauvin, a white officer captured on cellphone video kneeling on the handcuffed Floyd's neck for more than nine minutes, was found guilty of murdering Floyd in 2021.
With Chauvin kneeling on Floyd's neck, and Lane and Kueng restraining his knees and buttocks, Floyd pleaded for his life before falling limp.
Two other former officers, Thomas Lane and J. Alexander Kueng, pleaded guilty last year to aiding and abetting second-degree manslaughter, the same charge Thao faced.
At a federal trial last year, Keung, Lane and Thao were found guilty of violating Floyd's civil rights.