OKLAHOMA CITY (AP) — A federal appeals court has delayed a hearing in which an Oklahoma death row inmate is expected to make a final plea for mercy before his scheduled execution.

The three-member panel of the U.S. Court of Appeals for the 10th Circuit delayed Monday’s scheduled hearing of the Pardon and Parole Board. The panel was set to meet to consider Kevin Underwood’s clemency bid.

Two of the board's members have resigned in recent weeks, and Underwood’s attorneys claim he has a right to a hearing before a full five-member board. One of Gov. Kevin Stitt's appointees to the board, Calvin Prince, resigned after coming under criminal investigation by the Oklahoma State Bureau of Investigation for alleged “inappropriate activities,” according to a letter Pontotoc County District Attorney Erik Johnson sent to the state's attorney general. Prince has not been formally charged with any crime. Another of Stitt's appointees, Edward Konieczny, also stepped down from the board last month.

Prince’s attorney, Larry Balcerak, didn't immediately respond to a phone message seeking comment.

“The stay is frustrating but we are proceeding with all legal avenues to allow the hearing to take place this week and to keep the execution on schedule," Leslie Berger, a spokeswoman for the Oklahoma attorney general's office, said in a statement.

The 44-year-old Underwood is scheduled to receive a lethal injection on Dec. 19 for the 2006 slaying of 10-year-old Jamie Rose Bolin, who lived in Underwood's apartment complex in Purcell, Oklahoma.

Underwood admitted to investigators that he killed the girl as part of a cannibalistic fantasy, although there was no evidence that any cannibalism took place. The girl's body was found in a plastic tub in Underwood's apartment, and her head had been nearly cut off.

Underwood's attorneys don't deny that he killed the girl, but they claim he suffered from mental illness that included a “deeply disturbed fantasy life that he eventually acted upon.”