An Oklahoma man sentenced to die for killing his 9-month-old daughter in 2002 has become insane while in prison, and his upcoming execution should be halted, the man's attorneys argue in a new court case.

Attorneys for Benjamin Robert Cole, 50, of Claremore will present their arguments Friday before District Judge James Bland in McAlester, where Cole is being housed at the Oklahoma State Penitentiary.

"Mr. Cole's condition has deteriorated steadily since his conviction," Federal Public Defender Susan Otto wrote in a court filing.

The U.S. Supreme Court has held that executing an insane person is unconstitutional, and Cole's attorneys maintain the prison's warden is violating a state law that requires her to notify the local district attorney when an inmate has become insane.

Otto says Cole's ability to participate in his defense has been in question since the inception of the case, and she told the state's Pardon and Parole Board last week during a clemency hearing that Cole once went two years without showering or leaving his cell.

But Warden Anita Trammel wrote in an affidavit this week that she spoke to Cole about several topics recently and that he understands why he's being executed.

"Mr. Cole expressed to me that he understood he was being executed by lethal injection for the murder of his daughter," Trammel wrote.

"Mr. Cole was well versed in religion and we also discussed certain current events and his time in the Air Force."

But a forensic psychiatrist hired by Cole's attorneys, Dr. Raphael Morris, testified at Cole's clemency hearing last week that Cole sat before him in a catatonic state during an hour-long visit at the penitentiary and didn't make eye contact or utter a single word.

The Pardon and Parole Board voted 3-2 against recommending clemency to the governor, who could only have granted clemency with a recommendation from the board.

But even a clemency recommendation would have been no guarantee that Gov. Mary Fallin would have spared his life. The board voted 4-1 to recommend clemency for death row inmate Garry Allen, but Fallin still rejected the recommendation and said his execution should proceed.

Allen, who suffered a brain injury after being shot in the head during his arrest, appeared confused during his 2012 execution and seemed startled when a prison official announced the start of the lethal injection.

Cole is scheduled to be executed by lethal injection Oct. 7 after being convicted of first-degree murder in Rogers County for killing his daughter, Brianna Cole, whose spine was broken and her aorta torn after she was forcefully bent backward. Cole has not denied killing the child.

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