Convicted murderer Dylann Roof will not ask jurors to take his mental health into consideration next month during the death penalty phase of his trial for killing nine black churchgoers in Charleston, South Carolina.

In a handwritten note filed in a South Carolina federal court on Friday, Roof, an avowed white supremacist, wrote, "I will not be calling mental health experts or presenting mental health evidence."

Roof was found guilty on Thursday of 33 charges of federal hate crimes after a six-day trial featuring harrowing testimony about the night of June 17, 2015, when he attended Bible study at Emanuel African Methodist Episcopal Church before opening fire on the parishioners.

He spent months scouting potential sites for the attack, which he confessed to carrying out, and wrote a journal and online manifesto filled with hatred toward Jewish and black people.

Roof's decision not to call mental health experts or present mental health evidence came after he called the field of psychology a "Jewish invention" in his journal, part of which was read aloud at his trial earlier this month.

"I am morally opposed to psychology. It is a Jewish invention that does nothing but invent diseases and tell people they have problems when they don't," Roof wrote.

The jury is scheduled to begin hearing evidence on Jan. 3 in the second phase of the trial, which will determine whether Roof faces execution.

Roof is acting as his own lawyer in that proceeding.

He still faces a trial next year on state charges in connection with the church killings. South Carolina prosecutors have said they intend to seek the death penalty as well.