* Senator says gunman's wife is "person of interest" in probe
* Too soon to say if anyone will be charged-federal prosecutor
* New calls for limits on gun purchases by buyers on watch lists

US investigators have questioned the wife of the gunman who killed 49 people at an Orlando gay nightclub, the FBI said on Wednesday, and a law enforcement source said she could face criminal charges if there is evidence of any wrongdoing.
Omar Mateen's wife, Noor Salman, knew of his plans for what became the deadliest mass shooting in modern US history, said the law enforcement source, who has been briefed on the matter.
"With respect to the wife, I can tell you that is only one of many interviews that we have done and will continue to do in this investigation," FBI Special Agent Ron Hopper told a news conference. "I cannot comment on the outcome or the outcome of that investigation."
The Federal Bureau of Investigation wanted to hear from anyone who had contact or information about the gunman, Hopper said.
In Washington, Sunday's shooting in Florida stirred fresh debate on gun purchases in the United States, after it emerged that Mateen was legally able to buy an assault rile even though the FBI had investigated him in the past for possible ties to Islamist militant groups.
US Senator Angus King, a member of the Senate Intelligence Committee, which received a briefing on the investigation into the massacre, told CNN it appeared Salman had "some knowledge" of what was going on.
"She definitely is, I guess you would say, a person of interest right now and appears to be cooperating and can provide us with some important information," King said.
US Attorney Lee Bentley declined to say whether Salman or any other associates of Mateen's could face criminal charges.
"I am not going to speculate today as to any charges that may be brought or indeed whether any charges will be brought in this case," Bentley told the news conference. "It is premature to do so."
Salman was with Mateen when he cased possible targets in the past two months, including the Walt Disney World Resort in April, a shopping complex called Disney Springs and the Pulse nightclub in early June, CNN and NBC reported.
Salman could not be reached for comment.

Father supports FBI

The gunman's father, Seddique Mateen, declined to comment specifically on the investigation on Wednesday, saying, "The FBI, they always do a professional job and to the maximum extent of my ability I will support them."
The younger Mateen, a New York-born US citizen of Afghan heritage, was shot dead by police after a three-hour rampage through the Pulse nightclub. The attack was the deadliest on US soil since the hijacked plane attacks on New York and Washington on Sept. 11, 2001.
Federal investigators have said Mateen, who was 29 and worked as a security guard, was likely self-radicalized and there was no evidence he received any help or instructions from outside groups such as Islamic State.
Salman's mother, Ekbal Zahi Salman, lives in a middle-class neighborhood in Rodeo, California, about 25 miles (40 km) north of San Francisco. A neighbor said Noor Salman visited her mother only once after she married Mateen.
Noor Salman's mother "didn't like him very much. He didn't allow her (Noor) to come here," said neighbor Rajinder Chahal. He said he had spoken to Noor Salman's mother after the Orlando attack and she "was crying, weeping."
The shooting raised questions about how the United States should respond to the threat of violence from militant Islamists at home and abroad. The FBI questioned Mateen in 2013 and 2014 for suspected ties to Islamist militants but concluded he did not pose a treat.
Sunday's attack followed a mass shooting in San Bernardino, California, in December in which a married couple inspired by Islamic State killed 14 people.
US Senator Pat Toomey, a Republican who joined forces with Democrats in an unsuccessful push for gun control legislation after the killing of elementary school children in Connecticut in 2012, is now working on a bill to keep guns out of the hands of people on terrorism watch lists, a gun control group said on Wednesday.
Republican presidential candidate Donald Trump said he would meet with the powerful National Rifle Association lobbying group, which has endorsed him, to discuss a similar idea for restricting gun purchases. That marked a break with Republican Party orthodoxy, which typically opposes any restrictions on gun ownership.
The NRA responded on Wednesday it believed that people listed on terrorism watch lists should face additional reviews before purchasing firearms.
Presumptive Democratic presidential nominee Hillary Clinton has supported gun control efforts and said on Monday she was "bewildered" that congressional Republicans had blocked a Democratic effort to restrict gun sales to people on the watch lists.

'I am the shooter'

Mateen made multiple calls to 911 emergency services during his rampage, which he used to declare his allegiance to various Islamist militant groups, some of which are at odds with one another. He also called a local 24-hour cable news channel, News 13, the station revealed on its website on Wednesday.
Matthew Gentili, who was the producer on duty at the time, described the call in an interview with the station.
"'I'm the shooter. It's me. I am the shooter,'" Gentili described Mateen as saying. Gentili said Mateen also told him, "'I did it for ISIS. I did it for the Islamic State.'"
Autopsies have been completed on all 49 victims, and 35 bodies have been released to funeral homes, the Orange County Medical Examiner's Office said on Wednesday.
Orlando is one of the United States' most popular tourist destinations, with its theme parks helping to draw more than 60 million visitors a year. As the city mourned, a huge search was under way for the body of a 2-year-old boy who was dragged off by an alligator in a lagoon on Tuesday while visiting Walt Disney World with his family.