George A. Pettibone, one of the three members of the inner circle Western Federation of Miners accused by Harry Orchard of ordering the assassination of Frank Steunenberg, was a "rabid anarchist" with a history of violence. Pettibone had himself worked the silver mines of the Couer d'Alene and was one of four unionists prosecuted and convicted for his role in the 1892 unrest. (His conviction was overturned by the U. S. Supreme Court in 1893).  The gregarious, irreverent miner rose rapidly through the ranks of the WFM and by the late 1890's the organization was operating out of a household appliance store that Pettibone owned in Denver.  Above his store were rooms made available to out-of-town WFM members visiting the city.

Pettibone, according to Orchard, was the inventor of an extremely powerful incendiary substance called "Pettibone Dope" or "Hellfire." Orchard testified that Pettibone gave him two grips containing two quart bottles and three pint bottles of the Dope with orders to toss the bottles into railroad cars carrying non-union miners. When, however, Orchard discovered the the cars carrying the non-union miners also carried other, innocent passengers, he decided against throwing the bottles.

Orchard testified that Pettibone had ordered the assassination of mining company presidents, state supreme court justices, and governors, including Steunenberg.  Orchard said that Pettibone told him of the Steunenberg assignment, it would be "a very hard job in a little country town like Caldwell."

Pinkerton detectives code-named Pettibone "Rattler."  He took his arrest and incarceration cooly, if not even cheerfully. As he assumed his new quarters with his two colleagues on Idaho's death row, Pettibone shouted, "There's luck in odd numbers, said Barney McGraw!"

Pettibone was tried for murder following the acquittal in the Haywood case. In March, 1908, Pettibone also was acquitted, ending the government's efforts to prosecute the WFM's inner circle.