The state of Missouri executed Cecil Clayton, 74, on Thursday night. Earlier that evening, the United States Supreme Court and Missouri Governor Jay Nixon had both denied last-minute requests to delay the execution. Lawyers for Clayton, who is missing part of his brain, argued their client was mentally disabled and should have avoided the death penalty.

Clayton was injured in a 1972 sawmill accident, which forced surgeons to remove a fifth of his frontal lobe, which, among other things, controls problem solving, memory, judgment and impulse control. Two decades later, Clayton was sentenced to death for the 1996 killing of Christopher Castetter, a sheriff’s deputy in Purdy, Missouri. Clayton’s attorneys did not argue their client was innocent; they said he should be spared execution because of his mental disabilities. A 2004 test determined Clayton’s IQ to be 71.

“Mr. Clayton’s IQ, since his accident and subsequent deterioration, now falls within the range required for intellectual disability,” the lawyers wrote to the Court, according to NBC News. “And there is substantial evidence of adaptive deficits; Mr. Clayton, even in prison, cannot without assistance order canteen items or navigate the telephone system.”

In 2002, the Supreme Court ruled that executions of the mentally disabled violate the Constitution’s ban on cruel and unusual punishment. The ruling, however, did not specify how states should go about determining mental disability. The state of Missouri argues Clayton is competent enough.

“This crime was brutal and there exists no question of Clayton’s guilt,” Nixon said in a statement denying clemency.

As noted by the Guardian, Missouri is now one of the nation’s most aggressive states when it comes to the use of capital punishment. Clayton is the 14th inmate executed in Missouri in the last 17 months.