Molly Maguire Executions. On June 21, 1877, four "Molly Maguires," an alleged secret society of Irish mine- workers, were hanged here. Pinkerton detective James McParlan's testimony led to convictions for violent crimes against the coal industry, yet the facts of the labor, class, and ethnic conflicts, even the existence of the organization, remain contested. Six others were hanged on this day at the county jail in Pottsville; ten more were executed in Pa. through 1879.