Petiot advertised his illicit services so blatantly that the Fly-Tox network was ripe for infiltration by early 1943. In fact, an informer named Charles Beretta had wormed his way into the operation, feeding names to the Gestapo as he went. In May, Nazis arrested Raoul Fourrier, Edmond Pintard and René-Gustave Nézondet, torturing them until they identified Marcel Petiot as “Dr. Eugène.” Petiot joined the others in prison at Fresnes. Although Nazis searched his home and other property, they somehow missed the charnel house on Rue le Sueur. Nézondet was released two weeks later, but Petiot, Fourrier and Pintard spent a total of eight months in prison. They were tortured repeatedly, but staunchly refused to betray members of the Resistance.

In fact, based on the tales Petiot spun at his murder trial, in 1946, his stubborn silence may have sprung from simple ignorance. The “hero” had no names to offer his captors, since he played no significant role in the Resistance movement, and any confession of his Fly-Tox operation was tantamount to suicide. Frustrated, the Nazis released Fourrier, Pintard and Petiot in early January 1944. Ironically, the months of torture and confinement provided Petiot with his best cover yet--but his time was running out. By March, his chamber of horrors on Rue le Sueur was exposed and Petiot himself had vanished.

Loyal patients and friends were the keys to Petiot’s survival as a fugitive. They shuttled him from one address to another in Paris while he cultivated a beard, and adopted one name after another to conceal his movements. Eventually, Petiot found a home with patient Georges Redouté. Petiot convinced Redouté that the Gestapo wanted him for killing “Germans and informers.” While living with Redouté, Petiot ventured out only at night; sometimes returning with weapons claimed to have been captured from Nazi patrols.

Parisian police went on strike in August 1944, besieged at their Préfecture by German tanks and troops. That month Petiot, calling himself “Henri Valéri”, joined the new French Forces of the Interior (FFI). He was promptly commissioned as a captain, in charge of counterespionage and interrogation of prisoners in the Reuilly district of Paris. The French capital was liberated the next month and collaborators were purged, with Petiot/Valéri in the thick of the action.

His cover began to unravel in September, when two FFI soldiers from Petiot’s unit robbed the elderly mayor of Tessancourt, stealing F12.5 million in cash and collectable stamps from his home before killing their victim in front of witnesses. Three youths reported the crime to Petiot, who promptly tossed them in jail. An FFI lieutenant tried to investigate, but was ordered off the case by Capt. Valéri. The bandits were briefly detained, then released. The thieves disappeared as well as the money.

Three days after the robbery-murder the newspaper Résistance published a scathing article on fugitive Petiot. The story called him a “soldier of the Reich” who had allegedly donned a German uniform to hunt down French patriots around Avignon in March 1943. Attorney René Floriot, Petiot’s defense counsel in the 1942 narcotics cases, received a letter from his fugitive client which condemned the Résistance article as a collection of “filthy kraut lies.”

While the letter was false, Petiot’s letter convinced authorities that he was still in Paris. A new search began, with FFI Captain Henri Valéri among the officers drafted to hunt for Petiot.

Petiot’s luck ran out at 10:15 a.m. on Oct. 31, when Petiot was recognized and arrested at a Paris metro station. He carried a pistol, F31,700 in cash, and 50 documents in six different names. Petiot’s long run was over, but the search for the truth had just begun.