Nothing like a big dose of the macabre for the weekend. In 1938, a scientist actually recorded a condemned prisoner's heartbeat as he was being executed by firing squad.
Doctor Stephen Besley was a doctor at a prison. He was, perhaps, not the most sympathetic of physicians, but he was extremely practical. After seeing many prisoners executed, it occurred to him that these were unique opportunities to observe what vital signs were when a person is knowingly waiting for certain, violent death. Wanting to take advantage of it, he began asking prisoners for permission to record their heartbeats as they were being executed.
John Deering gave his permission. This might seem strange, but Deering did a lot of strange things. He had been facing lesser charges in Michigan, but decided that 'the world was better off without him' and sought a capital charge. He confessed to murdering someone in Utah, was moved to the Utah legal system, and sentenced to death. The sentence was carried out on Halloween in 1938. Deering appeared calm while Besley attached heart monitors to his wrists, and while prison officials attached a target to his chest. Appearances were deceptive. His heart was going three times the normal resting heart rate, and only partially slowed after he had said his last words. He was shot by five executioners, and his heart stopped about fifteen seconds after the shots.
So, we now know that people about to be executed are afraid. Go science.