The man arrested for the brazen murder of British MP Jo Cox has been a supporter of both a neo-Nazi group in the United States and a pro-apartheid South African publication, according to reports.

Thomas Mair, 52, was arrested shortly after Cox was shot and stabbed Thursday. Yorkshire Police say they are “not looking for anyone else in connection with the incident.”

Cox, 41, was attacked and killed outside a library in her northern England constituency and was pronounced dead at 1:48 p.m.

Electoral records show Mair lives in the area of Birstall where the killing occurred and photos posted on social media show two police officers subduing a man lying on the street.

The Southern Poverty Law Center (SPLC) has reported that Thomas Mair was a longtime supporter of an American white nationalist group, the National Alliance.

It was once considered the premier neo-Nazi organization in the U.S. and Oklahoma City bomber Timothy McVeigh based his attack that killed 168 people on a truck bombing described in a book written by the group’s founder.

The SPLC, a nonprofit legal group specializing in civil rights, said Mair bought a manual from the National Alliance in 1999 that included instructions on how to build a pipe pistol out of components readily available at hardware stores.

Witnesses to the attack on Cox said it appeared the perpetrator had either an antique or homemade gun.

Mair also bought an illustrated handbook written by Adolf Hitler that was given to new Nazi party members in the 1940s.

It included pictures of receipts in Mair’s name in its report. The address on receipts corresponded to a house that on Friday was cordoned off by police tape and guarded by uniformed officers.

A local paper, Batley and Birstall News, said Mair was a volunteer in Oakwell Hall County Park in Bristall. The article says Mair had said the volunteering had done him more good than all the physiotherapy and medication in the world.

According to The Yorkshire Evening Post, David Pickles, a neighbour to the suspect said: “I still can’t believe it. He’s the last guy I would have thought of. He’s just quiet. He kept himself to himself."

Pickles said Mair had lived alone for 20 years. “He did a lot of people’s gardens round here. But he did it quietly.”

The Daily Telegraph said Mair’s brother said the suspect “has a history of mental illness” but had not displayed violence or expressed extreme political views.

The London-based paper said Mair was a subscriber to S.A. Patriot, a South African magazine published by a pro-apartheid group opposed to “mulit-cultural societies” and “expansionist Islam.”

In a statement to London journalist Olly Barratt, the group said it was “appalled and sickened” by Cox’s murder. The group said Mair subscribed to their magazine in the mid-1980s but paid for only a few editions.

Cox was a former aid worker who had championed the cause of Syrian refugees and campaigned for Britain to stay in the EU when it votes in a referendum June 23.

The referendum has sparked an intense debate about immigration and Britain's place in the world.

Both sides have suspended campaigning in the wake of the killing.