The oldest man on death row in the US state of Missouri has been executed by lethal injection.

He was 74-year-old Cecil Clayton, sentenced to death for shooting a sheriff’s deputy in 1996. Clayton had brain damage from a 1972 sawmill accident, and suffered from dementia.

Clayton shot in the forehead Christopher Castetter, who was aged 29 and a father of three children. His lawyers argued that, as surgeons removed about 20% of his brain’s frontal lobe – the bit responsible for impulse control and judgement – following his accident, which left him with an IQ of 71, then he was ineligible for execution. Psychiatric evaluations indicated Clayton did not understand why he was to be executed.

Apparently Clayton believed that at the last moment God would rescue him and that he would travel the country playing the piano and preaching the gospel.