Attorneys are asking the U.S. Supreme Court to block the scheduled execution of a Texas death row inmate whom they describe as delusional.

Lawyers say the high court should extend the ban on executing mentally impaired people to those who are mentally ill, such as 33-year-old Adam Ward.

Ward is facing lethal injection Tuesday evening for fatally shooting a code enforcement officer in the North Texas city of Commerce. The officer had been taking photos of junk piled up outside the Ward family home, about 65 miles northeast of Dallas.

Ward says the shooting nearly 11 years ago was in self-defense.

He would be the ninth convicted killer executed in the U.S. this year and the fifth in Texas, which carries out capital punishment more than any other state.