 "Omar Mateen")
Omar Mateen, the lone gunman who killed 50 people at a gay nightclub in Orlando on Sunday, was opposed to homosexuality and allegedly engaged in domestic violence, media reports citing his relatives said.
In the worst mass shooting in US history, Mateen's rampage left 50 people dead and another 53 wounded, before he was killed by police.
Sunday's horrific incident eclipses the 2007 massacre at Virginia Tech university, which left 32 people dead in its wake.
Preliminary reports have brought to light details about 29-year-old Mateen, a Muslim American of Afghan descent.
Here is what we know about Mateen so far:
1) Homophobe: Mateen's shocked father, Mir Seddique, said his son had recently taken offence when he saw two gay men expressing affection on a Miami street.
"We were in downtown Miami, Bayside, people were playing music," the father told NBC News in the immediate aftermath of the shooting, adding, "And he (Mateen) saw two men kissing each other in front of his wife and kid and he got very angry."
2) Domestic violence: "He was not a stable person," Mateen's ex-wife told the Washington Post, which did not identify her because she fears for her safety.
"He beat me. He would just come home and start beating me up because the laundry wasn't finished or something like that," she told the newspaper.
According to her account, the pair had met in New York but in March 2009 had moved in together in Fort Pierce, Florida.
The woman's parents later rescued her from the relationship and the pair were later divorced, according to a court document seen by AFP.
3) Family says not overtly religious: Relatives of Mateen interviewed by US media say he was not overtly religious. "This had nothing to do with religion," Mateen's father said following the shooting.
According to Mateen's ex-wife, in the few months they were married he gave no signs of having fallen under the sway of radical Islam. She added that he was not especially expressive about his Muslim faith.
4) The FBI had investigated him twice before: According to the Daily Mail, the Federal Bureau of Investigation (FBI) had named Mateen "a person of interest in 2013 and again in 2014".
According to the report, the agency first investigated him in 2013 when "he made 'inflammatory remarks' to colleagues alleging possible terrorist ties".
Quoting a FBI special agent, the report said that after interviewing witnesses, physical surveillance and interviewing Mateen twice, the agency was "unable to verify the substance of his comments" and the "investigation was closed".
The report said that Mateen came under the FBI's scanner a second time in 2014, when agents interviewed him "about a potential connection he may have had with American suicide bomber Moner Abu Salha, who lived about 30 minutes away in Vero Beach, Florida".
The report said that according to the FBI agent it was determined that Mateen had "minimal" contact with Salha and it did not "constitute a substantive relationship or threat at that that time".
5) Police say Mateen claimed allegiance to ISIS: Mateen, according to a NBC News report, called the emergency police number before the attack and expressed "fealty" to ISIS.
Citing statements from law enforcement officials, the report said that Mateen also mentioned the Boston Marathon bombers, Dzhokhar Tsarnaev and Tamerlan Tsarnaev.
