One of the brothers of the Boston bombings was in possession of right-wing American literature shortly before the deadly attack, it has emerged.
Tamerlan Tsarnaev was understood to have read articles that argued 9/11 and the 1995 Oklahoma City bombings were government conspiracies, along with an article on "the rape of our gun rights".
The BBC's Panorama programme spoke with friends of the suspected bombers in an attempt to discover why Tamerlan, 26, and his brother Dzhokhar Tsarnaev, 19, turned to radical jihadism.
According to the BBC, he also read texts that examined the motivations behind mass killings and looked at how murderers can dispassionately hurt and kill others. There was also material discussing the plight of prisoners still trapped in Guantanamo Bay and on US drone activity.
When reading material on white supremacy he allegedly commented that "Hitler had a point".
Friends of the brothers told the programme that Tamerlan had become passionate about Islam after feeling frustrated at his faltering boxing career, having been barred from contesting at a national level because he didn't have American citizenship.
Both brothers had visited militant Islamic websites before the bombing.
One friend, who asked to remain anonymous for fear of being associated with terrorism, said Tamerlan "just didn't like America". “He felt like America was just basically attacking all Middle Eastern countries…you know trying to take their oil,” he said.
A spokesperson from the mosque Tamerlan attended in Cambridge, Boston, said he rarely worshipped there and seemed to be a "Muslim of convenience".
Friends revealed the relationship between the two brothers may have been more fractured than previously thought, with Tamerlan allegedly disapproving of his the amount of marijuana his brother smoked and for not praying regularly. 'Tito' told the programme Tamerlan didn't approve of Dzhokhar's “party lifestyle”.
“He (Dzhokhar) was intimidated", Tito added, "that would probably be the best word. He took him very seriously. He was an authority.”
The brothers are suspected of detonating a bomb at the Boston Marathon on 15 April, killing three people and injuring over 260. In the ensuing manhunt both brothers engaged in a shoot-out with police, during which Tamerlan was killed and an MBTA police officer was critically injured.
Dzhokhar has pleaded not guilty to an array of charges connected to the bombings.
The Brothers who Bombed Boston will be shown today at 8.30pm.