(Reuters) - Dylann Roof, the white supremacist who killed nine black people at a South Carolina church in 2015, has appealed his conviction and death sentence, with lawyers arguing he was too mentally ill to stand trial or represent himself at sentencing.

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“Roof’s crime was tragic, but this Court can have no confidence in the jury’s verdict,” says his appeal, filed with the 4th U.S. Circuit Court of Appeals on Tuesday.

A jury found Roof guilty of 33 federal charges, including hate crimes resulting in death, for the shocking mass shooting at the landmark Emanuel African Methodist Episcopal Church in Charleston in June 2015.

Roof dismissed his defense attorneys just before trial and represented himself during jury selection. At the last minute he reinstated his lawyers for the guilt phase but represented himself again for the penalty phase.

The same jury that found him guilty also gave him the death penalty in January 2017 after deliberating for less than three hours.

Federal public defenders representing Roof said in a 321-page brief that when Roof represented himself he was a “22-year-old, ninth-grade dropout diagnosed with schizophrenia spectrum disorder, autism, anxiety, and depression, who believed his sentence didn’t matter because white nationalists would free him from prison after an impending race war.”

Roof had been cooperating with his trial lawyers for 16 months, but suddenly objected when he learned they planned to present him as “developmentally disabled or mentally ill.”

In a competency hearing, five experts testified that he showed a wide range of mental health symptoms, but when Roof addressed the hearing he told the judge he instructed his lawyers to stop suggesting he had any mental problems, the brief said.

U.S. District Judge Richard Gergel nonetheless found him competent, saying he was “cogent and articulate” when he addressed the court and “this defendant has an extremely high IQ.”

In allowing him to represent himself, Gergel said, “I continue to believe it is strategically unwise, but it is a decision you have the right to make.”

The U.S. Supreme Court affirmed a defendant’s Sixth Amendment right to act as his own lawyer in the 1975 decision Faretta v. California.

But Roof’s lawyers say that decision and subsequent ones set limits on self-representation.

The 2008 decision Indiana v. Edwards allows judges to force a lawyer on defendants who lack mental capacity, they said.

“The choice is not all or nothing,” the lawyers said, citing the 2018 ruling in McCoy v. Louisiana.

(This story corrects stages at which Roof represented himself)