As families await to hear word of their friends and loved ones following Sunday's shooting at the Pulse nightclub in Orlando, details continue to emerge surrounding Omar Mateen, who — armed with a semiautomatic rifle and pistol — killed 49 people and wounded 53 others before being gunned down in the deadliest the deadliest mass shooting in U.S. history.
Here's what we know so far:
* Born in New York in 1986, Mateen moved with his family to Florida, where he spent at least part of his childhood.
* He took classes at Indian River State College in Fort Pierce and in October 2006 got a job as a prison guard for the Florida Department of Corrections. He didn't last long in the position. Records show he left the job in April 2007 for an "administrative matter unrelated to misconduct."
* Since 2007, Mateen had worked as a licensed security officer for G4S, one of Florida's largest private security companies. One of his assignments was at courthouse in St. Lucie County where he worked until some time in 2013, according to Joseph Abreu, communications manager for the Clerk of the Circuit Court of St. Lucie County.
* He married Sitora Yusufiy in 2009 and divorced two years later. She described him as unstable and abusive. She also said he was bipolar.
* He is the father of a young boy.
* He was the son of an Afghan immigrant, Seddique Mir Mateen, who had a talk show in the United States, the nature of which was not entirely clear: A former Afghan official said the program was pro-Taliban and a former colleague said it was enthusiastically pro-American.
* Mateen had become increasingly withdraw from the world, according to public records and interviews with neighbors, coworkers and family friends.
* The FBI interviewed Mateen at least three times in recent years, but was unable to find any incriminating evidence, said Ronald Hopper, an assistant agent in charge of the bureau's Tampa Division. The agency ultimately closed its investigations.
*Officials with the federal Bureau of Alcohol, Tobacco, Firearms and Explosives said he legally bought two firearms in the past week — a long gun and a handgun — but declined to say where.
* FBI officials suggested Mateen acted alone and said they were not searching for a second gunman.
* In an interview with NBC News, Mateen's father said his son was likely motivated not by religious extremism, but by his hatred of gay people.
* Mateen had begun to act more and more devout in recent years but still was capable of sudden vulgarity and flashes of anger at gay people, blacks, Jews and women.
WHAT WE DON'T KNOW
* Law enforcement officials have not said whether Mateen had any direct link to the Islamic State, such as training or any sort of direct communication. The statement by the Islamic State did not provide details about its relationship with Mateen. However, FBI Director James Comey said today that Mateen had "strong indications of radicalization" and "potential inspiration by foreign terrorist organizations."
* It is possible he was "self-radicalized" — that is, claimed allegiance to the Islamic State but had no direct tie — like the husband and wife team behind the San Bernardino attack last year.
* The police in Santa Monica, Calif., arrested a heavily armed man who said he was in the area for the gay pride parade in West Hollywood, but they did not know of a connection between him and the Orlando attack.
Information from Times wire services was used in this report.