Federal prosecutors urged a judge Friday to reject former Minneapolis police Officer Derek Chauvin’s attempt to overturn his civil rights conviction in the 2020 murder of George Floyd.

Chauvin filed his motion in federal court in November, saying new evidence shows that he didn’t cause Floyd’s death, and alleging ineffective counsel by his defense lawyer. He said he never would have pleaded guilty to the charge in 2021 if his attorney had told him about the idea of two doctors, who weren’t involved in the case, who theorized that Floyd did not die from Chauvin’s actions, but from complications of a rare tumor.

Floyd, who was Black, died on May 25, 2020, after Chauvin, who is white, kneeled on his neck for 9 1/2 minutes on the street outside a convenience store where Floyd tried to pass a counterfeit $20 bill. A bystander video captured Floyd’s fading cries of “I can’t breathe.” Floyd’s death touched off protests worldwide, some of which turned violent, and forced a national reckoning with police brutality and racism.

Chauvin asked U.S. District Judge Paul Magnuson, who presided over the federal case, to throw out his conviction and order a new trial, or at least an evidentiary hearing. Chauvin filed the motion from prison without a lawyer.

In a response filed Friday, lawyers from the U.S. Attorney’s Office for Minnesota and the Justice Department’s Civil Rights Division urged Magnuson to deny the request without a hearing.

They pointed out that Chauvin knowingly and voluntarily waived his appeal rights when he changed his plea to guilty. And they said he failed to show that his attorney’s performance was deficient, even if the outside doctors had contacted him and even if the attorney did not tell Chauvin. They said the evidence proved that Chauvin caused Floyd’s death.

“The claims Defendant argues that counsel failed to raise are baseless, and counsel cannot be ineffective for failing to raise baseless claims,” they wrote.

The U.S. Supreme Court rejected Chauvin’s appeal of his state murder conviction in November, a few days after Chauvin filed his motion to overturn his federal conviction. He is recovering from being stabbed 22 times by a fellow inmate at the federal prison in Tucson, Arizona, in late November. He is serving his 20-year federal civil rights and 22 1/2-year state murder sentences concurrently.