Chauvin, who knelt on Floyd’s neck for about nine minutes May 25, is already charged with second-degree murder, which carries a maximum sentence of 40 years, as well as second-degree manslaughter. The third-degree murder charge carries a maximum sentence of 25 years.
Prosecutors had requested third-degree murder be added to former Minneapolis officer Derek Chauvin’s charges, which already included second-degree murder and manslaughter.
A judge has now granted the request and the trial begins on Monday.
Chauvin pressed his knee against Mr Floyd’s neck for nine minutes and then after die.

Hennepin County Judge Peter Cahill had earlier rejected the charge of third-degree murder in the case of Chauvin because of wording in the law that references an act “eminently dangerous to others”.
Mr Cahill said it was not appropriate for the case because Chauvin’s conduct could be construed as not dangerous to anyone apart from Mr Floyd.
The lawyers said the ruling established precedent that such a charge could be brought in a case where only a single person is endangered.
Mr Cahill said : “I feel bound by that and I feel it would be an abuse of discretion not to grant the motion.”
Jury selection resumed on Thursday ahead of the trial, with five jurors seated after two days of screening by lawyers and the judge.
Jemma Griffith ( national reporter for News Daily America).