ST. LOUIS (AP) – Missouri’s oldest death row inmate is asking the U.S. Supreme Court or the governor to spare him from being executed as scheduled Tuesday for the 1996 shooting death of a sheriff’s deputy.

Attorneys for 74-year-old Cecil Clayton argue in last-minute appeals that he has dementia and lingering effects from a 1972 sawmill accident that forced surgeons to remove part of his brain.

Clayton’s attorneys are seeking a competency hearing, and said Clayton isn’t mentally fit to be put to death.

Clayton was convicted of gunning down sheriff’s deputy Christopher Castetter in rural southwest Missouri’s Barry County while Castetter was investigating a report of a suspicious vehicle.

The Missouri Supreme Court on Saturday declined to intervene.

A spokesman for Gov. Jay Nixon said only that the Democrat is weighing Clayton’s clemency request.