An apparent online leak of materials from influential neo-Nazi website Iron March, which has linked to several murders and acts of extremist terrorism, has the potential to identify hundreds of extremists around the world.

The material, posted anonymously to an online archiving site on Wednesday, US time, by a user identified only as “antifa-data”. It apparently comprises the contents of the now defunct Iron March website’s underlying database and makes it possible to match usernames with email addresses, IP addresses, forum posts and direct messages.

Material uncovered in the leak so far suggests some users on the platform registered with existing personal email addresses, including addresses associated with several US universities. Posts and direct messages suggest that some members were on active military service at the time they posted, according to the open source journalism website Bellingcat.

By Wednesday evening on social media, researchers were claiming to have identified several individual users by means of the leak, including a one-time congressional candidate.

Iron March was founded in 2011 by a Russian nationalist named Alexander “Slavros” Mukhitdinov, and abruptly closed without explanation in November 2017.

Members and groups associated with the website were involved in a range of deadly violence after the site’s founding as influential users became more voluble in their support of uncompromising extremism, genocide and insurrectionary terrorism.

In May 2017, Iron March user and Atomwaffen Division (AWD) member, Devon Arthurs, murdered two roommates – and AWD comrades – in Tampa, Florida. Police found neo-Nazi literature in the house, along with explosives, radioactive materials, and a framed photo of the Oklahoma City bomber, Timothy McVeigh.

AWD has been tied to at least three other murders, a terror plot and the assault of a protester in Charlottesville.

Another group with links to Iron March is Vanguard America, the group that supporter James Alex Fields marched with at the Unite the Right rally in Charlottesville before he murdered Heather Heyer on 12 August 2017 by driving his car into the protesters.

According to the Southern Poverty Law Center, Iron March was “affiliated with or offered support to at least nine fascist groups in nine different countries”, including Serbia, Greece, Australia and Ukraine. The chats, too, appear to feature users from a range of different countries.

The website was also central to the development of “accelerationist” neo-Nazi ideology – which seeks to destabilize and replace liberal democracy by exacerbating its tensions with violence – and aesthetic of so-called Siege culture, which takes in skull masks and violent and racist memes.

In both respects, it has been influenced by the work of the American neo-Nazi James Mason, who joined the white power movement in his teens, in the 1960s.

Mason’s 1980s newsletters for the National Socialist Liberation Front were eventually compiled into a volume entitled Siege, which Iron March adopted as its central text. Among other things, Mason praised the murderer Charles Manson and Adolf Hitler and advocated the use of terrorist violence by decentralized neo-Nazi cells.

Iron March users came increasingly to advocate Mason’s ideas, which have become a touchstone in their subculture. Those ideas are now part of the DNA of neo-Nazi groups like AWD and The Base. Mason still lives in Denver, and has appeared in a recent AWD video.