FBI interviewed Orlando shooting suspect 3 times
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The FBI conducted three interviews of the man suspected of killing 50 people early Sunday morning in an Orlando nightclub, the deadliest mass shooting in U.S. history.

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An official said the FBI first became aware of the suspect, Omar Mateen, 29, in 2013 when he made "inflammatory comments to coworkers alleging possible terrorist ties."
In the course of that investigation, Mateen was interviewed twice, but the FBI was unable to verify the substance of his comments. 
 
The FBI interviewed Mateen, who was killed in Sunday's shootings, again in 2014. In that investigation, the FBI was looking into possible ties between Mateen and an American suicide bomber. The FBI determined that the contact did not constitute a threat at the time.
 
The investigations by the FBI are sure to inflame a rapidly evolving political debate about the nature of the violence and who is responsible. 
 
Fifty people were killed and 53 people were injured in Sunday's shooting at Pulse, a gay nightclub in Orlando, Fla. 
 
Mateen pledged allegiance to the Islamic State in Iraq and Syria (ISIS) before carrying out the assault, reportedly with an AR-15 style assault rifle and a handgun. ISIS also claimed responsibility for the attack, saying over an encrypted phone that it was carried out by one of its fighters.
 
NBC News reporter Pete Williams first reported that the gunman called 911 just before the killing spree began and pledged allegiance to ISIS leader Abu Bakr al-Baghdadi.

Obama, in a statement from the White House issued Sunday afternoon, called it an "act of terror and an act of hate." The killings at the gay nightclub occurred during Pride Month. 

The president said the incident is a “sobering reminder that attacks on any American, regardless of race, religion or sexual orientation, is an attack on all of us and on the fundamental values of equality and dignity that define us as a country.”
 
Obama also vowed a full investigation of the attack and canceled a planned campaign event in Wisconsin on Thursday with Hillary ClintonHillary Diane Rodham ClintonSessions says FBI agent Peter Strzok no longer has his security clearance Melania Trump puzzles with 'I really don't care' jacket Grassley wants to subpoena Comey, Lynch after critical IG report MORE, the presumptive Democratic nominee to replace him.
 
 
Trump, whose presidential campaign has been going through one of its toughest patches over the past two weeks, issued tweets and a statement that were unusual in their harsh criticism of the Obama White House. 
 
His comments also doubled down on the hard-line stance he has taken throughout the campaign against both legal and illegal immigration, which he argues has made the United States less secure. 
 
“In his remarks today, President Obama disgracefully refused to even say the words 'Radical Islam'. For that reason alone, he should step down,” Trump said. "If Hillary Clinton, after this attack, still cannot say the two words 'Radical Islam' she should get out of this race for the Presidency.”
 
Mateen was born in the United States, but his parents came from Afghanistan. In his statement, Trump said such immigration is endangering the country. 
 
"We admit more than 100,000 lifetime migrants from the Middle East each year. Since 9/11, hundreds of migrants and their children have been implicated in terrorism in the United States," Trump said.
 
"Hillary Clinton wants to dramatically increase admissions from the Middle East, bringing in many hundreds of thousands during a first term — and we will have no way to screen them, pay for them, or prevent the second generation from radicalizing.

"We need to protect all Americans, of all backgrounds and all beliefs, from Radical Islamic Terrorism — which has no place in an open and tolerant society," he said. "Radical Islam advocates hate for women, gays, Jews, Christians and all Americans. I am going to be a President for all Americans, and I am going to protect and defend all Americans. We are going to make America safe again and great again for everyone."
 
Trump previously called for a temporary ban on all Muslim immigration to the United States after terrorist attacks in Paris and San Bernardino, Calif. His standing in polls in the GOP primary went up after those attacks. 

Trump has come under criticism from his own party in recent weeks for comments suggesting a federal judge overseeing a case against Trump University is biased against him because of the judge's Mexican heritage. 

Speaker Paul RyanPaul Davis RyanPolitical figures pay tribute to Charles Krauthammer House approves five-year farm bill House postpones vote on compromise immigration bill MORE (R-Wis.), who called those remarks by Trump "the textbook definition of a racist comment," issued a statement on the Orlando attacks that refrained from criticism of Obama but said the U.S. was at war with Islamic terrorism.

"As we heal, we need to be clear-eyed about who did this," Ryan said in the statement. "We are a nation at war with Islamist terrorists. Theirs is a repressive, hateful ideology that respects no borders. It is a threat to our people at home and abroad. Our security depends on our refusal to back down in the face of terror. We never will."