We do not, and for the most part cannot, know precisely who is under the executioner’s hood. State secrecy statutes put the equivalent of a Harry Potter cloak of invisibility over these state-sanctioned killers. But litigation files and investigative journalism have revealed a number of executioners’ identities, allowing us to peek behind the veil of secrecy for a glimpse of who these people are.

Consider Missouri’s chief executioner from 1995-2006, Dr Alan Doerhoff, who was responsible for 54 of Missouri’s 65 executions between 1976 and 2006. He didn’t push the syringes – shockingly, non-medical prison guards did that – but he did most everything else. “Nobody will ever do as many [executions] as I have,” he would later boast.

Doerhoff’s identity was revealed when a lawyer for a condemned prisoner checked the prison’s chemical dispensary logs and discovered that 2.5 grams of sodium thiopental (the drug used to anesthetize the prisoner) had been used in previous executions. The state’s protocol called for 5 grams, double that amount. The prisoner sued.

Missouri doubled down on its executioner, telling the court that it was confident in his competence and planned to continue to use him in future executions. But the court rejected the state’s assurances, writing that it was “gravely concerned that a physician who is solely responsible for correctly mixing the drugs which will be responsible for humanely ending the life of condemned inmates has a condition which causes him confusion with regard to numbers”.

The state appealed, but soon thereafter, investigative journalism discovered Doerhoff’s identity. Jeremy Kohler with the St Louis Post-Dispatch broke the story in January 2008, and with it came another shocking revelation: Doerhoff had been sued for medical malpractice more than 20 times, and his hospital privileges had been revoked at two hospitals. Doerhoff had also been publicly reprimanded by the state medical board for hiding his malpractice suits from the hospitals where he practiced.