Current and former members of the U.S. military are among the ranks of one of America’s most extreme and violent white-supremacist groups, Atomwaffen, ProPublica reports. The investigative journalism site said it has identified three Atomwaffen members or associates who are currently enlisted in the Army or Navy, and three others who served in the armed forces in the past. Atomwaffen is considered one of the most extreme neo-Nazi organizations in the U.S. and has been linked to five killings, including that of a gay University of Pennsylvania student. The report identifies one Marine, Vasillios Pistolis, who bragged that he “cracked three skulls open” at the Unite the Right rally in Charlottesville, Virginia, last summer before returning to his everyday job. Another member, Joshua Beckett, who trained Atomwaffen members in firearms and hand-to-hand combat last fall, served in the Army from 2011 to 2015, according to service records.