ORLANDO - U.S. President Barack Obama was set to visit Orlando on Thursday to meet with survivors and family members of the 49 people killed in a gunman's rampage at a gay nightclub as authorities weighed whether to charge the assailant's wife.
Omar Mateen, a 29-year-old U.S. citizen born in New York to Afghan immigrant parents, also wounded 53 people in a three-hour-long rampage inspired by Islamic State militants that stands as the deadliest mass shooting in modern U.S. history.
The Federal Bureau of Investigation has interviewed Mateen's second wife, Noor Salman, who knew of his plans, according to a law enforcement source, and prosecutors were preparing to present evidence against her to a federal grand jury.
Salman has not commented publicly since the attack, which began around 2 a.m. early Sunday.
"I can assure you that we're working with our law enforcement partners to find out everything that we can about what happened at the Pulse nightclub," Lee Bentley, the U.S. Attorney for Florida's middle district said on Wednesday.
"We are using all law enforcement and legal tools to reconstruct not only the events of that night but the events of the past several months." Obama, accompanied by Vice President Joe Biden, will travel to Orlando in the latest in a long list of trips he has taken to console victims of mass shootings during his 7-1/2 years in office.
In December 2015, a married couple inspired by Islamic State shot dead 14 people in San Bernardino, California. "This will be, I think, an emotional trip," White House spokesman Josh Earnest told reporters.
"The president recognizes that he is a symbol for the rest of the country. But it would be impossible for him not to be personally affected by these kinds of conversations."
Mateen claimed allegiance to a variety of militant Islamist groups, including some at odds with each another, in a series of phone calls to 911 emergency services and a local cable television news channel during his rampage.
He appears to have self-radicalized and no evidence has emerged so far that his actions were directed by any outside groups, Obama has said.
Mateen carried out the slaughter with a legally purchased assault weapon and handgun despite twice being investigated by the FBI for alleged connections with terrorist groups.
The mass shooting renewed debate in Washington about gun control. Some Republicans including presumptive presidential nominee Donald Trump and U.S. Senator Pat Toomey suggested that people on federal watch lists who are banned from flying on commercial jets should not be allowed to purchase firearms.