Within a few hours on Sunday morning Omar Mateen established himself as the deadliest gunman in American history.
In the moments before he opened fire at the Pulse nightclub in Orlando killing at least 50 he telephoned police declaring allegiance to the Islamic State.
Any connection to foreign fighters has not been confirmed, however details of the religious 29-year-old’s past and interaction with US counter-terror authorities have begun to emerge.
A New York-born son of an Afghan immigrant, the body builder once aspired to become a police officer and worked as a security guard for global contractor G4S.
According to a childhood friend he was a playful youngster who grew serious in adulthood.
A father who had married twice, Mateen was said to attend evening prayer services at Orlando’s Islamic Centre three to four times a week with his young son.
Yet despite shying away from social interaction he was said to show no signs of violence, according to iman Syed Shafeeq Rahman.
The English and Farsi speaker had no criminal record and had been able to purchase several guns legally.
His father, Seddique Mir Mateen, a life insurance salesman, had a talk show on a California-based television channel.
The programme reportedly showed support for the Afghan Taliban while being pro-American.
In 2013 Mateen was interviewed twice by the FBI over inflammatory remarks he made to co-workers about extremism, although agents did not register any concerns at the time.
The following year officials found that Mateen had ties to an American suicide bomber, yet the connection was deemed to be minimal and the risk low.
However according to his ex-wife, Sitora Yusufiy, Mateen had a history of steroid abuse and was “mentally unstable” and physically abusive toward her.
She described a religious man who showed no signs of radicalism, adding of the nightclub massacre: “There was no sign of any of this at all.”