Boston bomber Tamerlan Tsarnaev, 26, killed in a shootout with police at Watertown, near Boston, was a boxer with a YouTube profile which carried controversial videos of Wahhabi Islamic preacher Feiz Mohammad, who is known for his fiery sermons that nourish hatred among his followers towards non-Wahhabis, something that he got taught in Saudi Arabia.
In 2007, the Australian Federal Police investigated whether 16 DVDs of Mohammed's sermons, called the Death Series, broke laws against sedition, racial vilification, and inciting violence and terrorism. He also featured in a British documentary called Undercover Mosque.
Feiz's parents emigrated from Lebanon to Sydney before he was born, and he has described his family as "so-called" Muslim -- hinting strongly that he disapproves of their level of commitment.
The future preacher competed as a boxer, bodybuilder, and horse trainer in his teens, and apparently used drugs before rediscovering his faith and moving to Saudi Arabia, where he studied Wahhabi Islamic law.
Upon his return to Sydney, Feiz founded the Global Islamic Youth Center in the suburb of Liverpool, reaching a community of more than 4,000 Muslims, and began to make the radical sermons which have earned international notoriety.
In 2007, a Channel 4 documentary entitled Undercover Mosque broadcast footage of Feiz urging children to become "soldiers defending Islam", adding "there is nothing more beloved to me than wanting to die as a Muhajid."
In 2010 he described Dutch politician Gert Wilders, an open opponent of Islam, as "evil filth" adding: "Anyone who mocks our learning, laughs at Islam, and degrades it must enter death -- decapitate him, cut off his head."
In sermons propagated on YouTube, Mohammad has cited alcohol, hip hop and consumerism as among society's greatest ills, and warned that "every innovation is misguided."
He has even claimed that Jewish people are pigs, and asserted that "anyone who tries to play with the sacred code of Shariah is a kafir... the only law for him is beheading, execution."
In a sermon on rape, made in March 2005, Mohammad told an audience - who had each paid $15 to see him - that a victim has "no one to blame but herself. She displayed her beauty to the entire world."