The doctors in the US who stand at the end of death row ready to oversee a punishment with no possibility of redemption are usually hidden in the shadows, their identities never revealed. 

But that has not been the case for Dr Mark Walton Fowler, whose involvement was unmasked last August after a Tennessee prison warden “inadvertently” let his name slip at the execution of death row inmate Byron Black. 

Witnesses had said that following the lethal injection, Black started breathing and sighing loudly, and after several minutes groaned in agony, saying, “It hurts so bad”. It took ten minutes before he was declared dead.

The 68-year-old former ED doctor has since found himself at the centre of public debate on the state’s use of the death penalty — and the controversial participation of doctors.