A photo released on Friday by the U.K.-based group Far Right Watch appears to show alleged killer Thomas Mair holding a "Britain First" banner at a rally hosted by the far-right extremist group.
The photo was released as U.K. authorities are looking into into eyewitness accounts that the man who killed Labour Party lawmaker Jo Cos shouted "Britain First" during the attack.
Eliot Higgins, founder of the crowdsourcing website Bellingcat, also pointed out on Friday that the apparent photo of Mair at a 2015 Britain First rally can be found on the group's website.
The photo allegedly showing the killer of Jo Cox at a 2015 extremist rally against Islam.
Britain First did not immediately respond to a request for comment from teleSUR.
Mair had a history of ties to extremist organizations in the United States. In 1999, he purchased books from a U.S. neo-Nazi group, the National Alliance, NA, on how to make a gun and improvised explosives, according to the Southern Poverty Law Center.
The center said it found that Mair ordered over US$620 worth of goods from NA's printing house, National Vanguard Books, and that Mair bought works on how to make improvised weapons, from bombs to guns.
“We are also aware of the inference within the media of the suspect being linked to right-wing extremism, which is again a priority line of inquiry which will help us establish the motive for the attack on Jo,” the West Yorkshire police department said in statement Friday.
Cox, a 41-year-old lawmaker for the Labour Party and a vocal advocate of Britain's European Union membership, died after she was shot and stabbed.