COLUMBIA, S.C. (AP) — Attorneys for convicted church shooter Dylann Roof have asked the U.S. Supreme Court to decide how to handle disagreements over mental illness-related evidence between capital defendants and their attorneys.

Authorities have said Roof opened fire during a 2015 Bible study at Mother Emanuel AME Church, killing nine members of the Black South Carolina congregation.

In their petition filed last month, Roof’s appellate team asked who gets the final say when the defendant has been ruled competent to stand trial, but their lawyer disagrees "on whether to present mitigating evidence depicting him as mentally ill," the Associated Press reported.

Roof fired his legal team and represented himself at sentencing, purportedly to keep jurors from hearing evidence about his mental health.

His attorneys say other courts would have allowed Roof to keep his attorneys while ensuring they didn't present evidence he didn't want.

Last year, an appellate panel unanimously upheld Roof's conviction and death sentence.

The government's response is due by the end of the month.

Roof is the first person sentenced to death in the U.S. for a federal hate crime, the Associated Press reported.

His attorneys filed an appeal, claiming Roof was not competent to stand trial, but the 4th Circuit Court of Appeals affirmed the conviction last August.

The families of the nine victims who were killed reached a settlement last October with the Justice Department due to a faulty background check allowing Roof to purchase the gun he used in the 2015 massacre.