President Barack Obama is going to Orlando, Florida, Thursday to honor the victims and meet with survivors of the worst mass shooting in U.S. history, in a display of solidarity with a city shaken by violence and horror.
The White House says that along with survivors of the massacre at a gay nightclub, the president will meet with the first responders to the attack, as well as doctors and surgeons treating the 53 wounded.
Meanwhile, the FBI says the wife of the man who killed 49 people at the Pulse nightclub, Omar Mateen, had some knowledge of his plans and may have failed to alert police.
A law enforcement official says a federal grand jury will consider whether to bring charges against the wife, Noor Zahi Salman.
Investigators say she went with Mateen on a "reconnaissance" mission to the club days before the shooting, and that she also accompanied Mateen to buy ammunition.
But police have told U.S. media that Salman warned her husband not to carry out the attack, as he left their home in Fort Pierce, Florida, Saturday to drive to Orlando.
A woman places a photograph of one of the victims in the shooting at the Pulse gay nightclub, on a memorial during an Interfaith Service at First United Methodist Church in Orlando, Florida, June 14, 2016.
Shooter reportedly cased other sites
There are also reports Mateen cased other sites, including a Disney World resort and shopping complex. But FBI agent Ron Hopper says there are no indications Mateen targeted anyplace else besides Pulse.
Authorities say the 29-year-old Mateen legally bought the weapons used in the attack earlier this month, including a semi-automatic assault rifle.
Some survivors and regular customers at Pulse have said Mateen was a frequent visitor there and tried to pick up other men, raising speculation by some who knew him from the club that he was a self-hating homosexual.
Hopper described the attack as both a hate crime and terrorism.
Mateen entered the club shortly before closing time early Sunday morning and began shooting. He also held a number of hostages in a bathroom. A police SWAT team drove an armored truck through a wall of the club, freeing the hostages and killing Mateen in the firefight.
The FBI investigated Mateen at least twice in 2013 and 2014 after he allegedly bragged to coworkers about ties to al-Qaida. Agents could not verify the allegations, and they closed their probe. Agent Hopper also said Mateen had minimal ties to American suicide bomber Moner Abu Salha, who was killed in Syria.
Mateen apparently pledged loyalty to the Islamic State group in 911 emergency phone calls he made during the attack, and also talked about the 2013 Boston Marathon bombing.
A woman throws a bouquet of flowers at a memorial for the victims of the shooting at the Pulse gay nightclub in Orlando, Florida, June 14, 2016.
Lawmakers demand answers
Several senators want to know more about the FBI's probe.
"We know that the FBI had looked closely at him because of concerns from coworkers and others," Democrat Debbie Stabenow told VOA. "I’d like to know more about their decisions. He was on a terror watch list and removed."
Senator Richard Durbin, another Democrat, said, “Not once but twice [the FBI was] warned that [Mateen] was a dangerous man. Their investigation concluded there was nothing more they could do. We wish there had been a different outcome – many people would be alive today."
Obama said U.S. law enforcement officials do everything to stop these kinds of attacks, but are "sobered" by how hard it is to try to detect "these lone actors" beforehand.
Orlando has been rocked by a string of deadly incidents in the past several days. The night before the Pulse massacre, a gunman shot and killed up-and-coming singer Christina Grimmie while she was signing autographs after a show in Orlando.
The shooter killed himself.
The city also was horrified Tuesday when an alligator attacked and killed a two-year-old boy at a Disney World man-made lake. Police recovered his body Wednesday.