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

Attorneys for 74-year-old Cecil Clayton argued 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 were seeking a competency hearing. They said he’s not 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.