On 25 October 1886, Duval broke into the mansion of a Parisian socialite and stole 15,000 francs before accidentally setting the house on fire. He was caught only two weeks later after trying to fence the stolen goods, stabbing a policeman named Rossignol several times during his arrest. (The policeman survived his wounds.) Duval's trial drew crowds of supporters and ended in chaos when Duval was dragged from the court, crying, "Long live anarchy!" He was condemned to death, but his sentence was later commuted to hard labor on Devil's Island, French Guiana.