There are strong indications the man who killed 49 people at a gay Orlando, Florida nightclub was radicalised, partly through the internet, but the FBI says he made some confusing claims about which groups he was supporting.
The deadliest mass shooting in recent US history ended with gunman Omar Mateen being shot dead after he opened fire in the Pulse nightclub killing 49 people and injuring 53.
FBI Director James Comey said Mateen, 29, - who had twice visited Saudi Arabia - reiterated his loyalty to jihadists during a call with emergency services the night of the attack
"He said he was doing this for the leader of ISIL (Islamic Front), who he named, but he appeared to claim solidarity with the perpetrators of the Boston marathon bombing, and solidarity with a Florida man who died as a suicide bomber in Syria for al-Nusra Front - a group in conflict with the so-called Islamic State."
Mr Comey said Manteen was investigated twice by the FBI, but dropped from any active watchlist, meaning he was able to buy firearms without the FBI being notified.
Mateen first came to the attention of the FBI in May 2013 when he was working as a contract security guard at a court house, and made some "inflammatory and contradictory" statements to coworkers about terrorism, he said.
"First he claimed family connections to al Qaeda. He also said he was a member of Hezbollah which is Shia terrorist organisation that is a bitter enemy of the so-called Islamic State, ISIL.
"He said he hoped that law enforcement would raid his apartment and assault his wife and child so he could martyr himself."
Mr Comey said the FBI investigated him for 10 months beginning in mid 2013.
They tried introducing him to confidential sources, recorded his conversations, followed him, searched his financial records, and interviewed those who knew him.
When the FBI interviewed him in early 2014, Mr Mateen said he made those statements in anger because his coworkers were discriminating and teasing him because he was Muslim, Mr Comey said.
His name surfaced again in an indirect way in July 2014, in relation to a Florida man who blew himself up in Syria as part of the al-Nusra Front.
Mr Comey said Mateen knew the bomber casually - they attended the same mosque - but he was interviewed again but no ties were found "of any consequence", and no further action was taken.
"We are also going to look hard at our own work to see whether there is something we should have done differently.
"So far the honest answer is 'I don't think so'... but we will look at it in an open and honest way and be transparent about it," Mr Comey said.
United States President Barack Obama said there is no evidence the Orlando nightclub killer was part of a larger plot, and described the attack as an act of home-grown extremism.
The presumptive US Democratic Party nominee Hillary Clinton said the United States should walk a fine line in bolstering security without demonising Muslims.
She called for tougher gun safety measures, and said she would enlist tech companies from Silicon Valley and Boston to help remove Islamic State messages from the internet.
And the Republican candidate Donald Trump reiterated his call for a temporary ban on Muslims entering the country but said it could be lifted once they were properly screened.
"We must find out what is going on," Mr Trump said in speech in New Hampshire.. "We need to tell the truth about how radical Islam is coming to our shores."
-RNZ / Reuters /BBC