Attorney Floriot appealed the conviction and sentence citing two complaints. First, he maintained that a mistrial should have been granted after Judge Leser and two jurors publicly declared their belief in Petiot’s guilt. Furthermore, Floriot charged, witness Marguerite Braunberger and her maid were perjurers. They lied in maintaining that Dr. Braunberger was dead, instead of hiding out in South America. All three points were rejected and Petiot’s death sentence was affirmed.

The day before that judgment was rendered, guards found an ampoule concealed in the Petiot’s prison uniform. They suspected it was cyanide, but the contents proved to be a sedative, smuggled into prison when Petiot arrived the previous October. The prisoner seemed calm, smiling as he asked his guards, “When are they going to assassinate me?” He refused to see a priest, preferring as he said to “take his baggage with him.”

Petiot had been scheduled to die on the day his appeal was rejected, but the guillotine malfunctioned that morning and his execution was postponed. At 3:30 a.m. May 25, a portable guillotine was delivered to the prison, assembled and ready to do its grim work by less than an hour later. Summoned from his cell, Petiot refused the traditional glass of rum but accepted a cigarette. He also agreed to meet with the prison chaplain for his wife’s sake, telling the minister, “I am not a religious man and my conscience is clean.”

Guillotine used in Petiot’s execution (Prison de la Sante Archives)

The closing ritual was swiftly completed. Petiot signed the register before his hands were bound, his neck shaved, and the collar cut from his shirt. He approached the guillotine calmly. Dr. Albert Paul, among the witnesses, noted that Petiot “moved with ease, as though he were walking into his office for a routine appointment.” Before he was strapped to the guillotine’s sliding table, Petiot warned the observers, “Gentlemen, I ask you not to look. This will not be very pretty.”

The blade dropped at 5:05 a.m. According to the witnesses, Petiot was smiling as his head tumbled into the basket.