COLUMBIA, S.C. (AP) — Attorneys for the man sentenced to federal death row for the racist slayings of nine members of a Black South Carolina congregation are set to formally argue that his conviction and death sentence should be overturned.

Federal court records show oral arguments have been set for May 25 before the 4th U.S. Circuit Court of Appeals in the case of Dylann Roof.

In 2017, Roof became the first person in the U.S. sentenced to death for a federal hate crime.

Authorities have said the self-avowed white supremacist opened fire during the closing prayer of a 2015 Bible study session at Mother Emanuel AME Church in Charleston, raining down dozens of bullets on those assembled.

Roof filed his appeal in 2017.

According to The Associated Press, Roof could file a 2255 appeal if his direct appeal to the 4th Circut is unsuccessful.

Roof could also petition the U.S. Supreme Court or seek a presidential pardon, the AP reported.