A gun store owner reported Orlando shooter Omar Mateen to authorities weeks before he committed the worst mass shooting in US history.

Robbie Abell, co-owner of Lotus Gunworks, told the Wall Street Journal Mateen came into the store in South Florida in May and asked for heavy-duty body armor like the kind used by law enforcement.

Staff at the store, which does not sell body armor, felt it was a strange demand.

After his request was denied, Mateen asked to buy bulk ammunition.

Though Lotus does sell ammunition, staff shut down his request and refused to sell him anything else.

They subsequently reported the incident to the FBI, Abell said.

Mateen had already been investigated by the FBI years before.

But even after Abell's report, the 29-year-old self-radicalized gunman obtained an AR-15 and a semiautomatic pistol from another store in the area, bought stacks of ammunition, then opened fire on Pulse nightclub, where he killed 49 people and wounded 53.

Robbie Abell, co-owner of Lotus Gunworks, told the Wall Street Journal Mateen came into the store in South Florida in May and asked for heavy-duty body armor

'Turned away': The owner of Lotus Gunworks claims Omar Mateen came into the store in South Florida in May and asked for heavy-duty body armor like the kind used by law enforcement, as well as bulk ammunition

The store's owner Robbie Abell told the Journal: 'The questions he was asking were not the normal questions a normal person would be asking…He just seemed very odd.'

Abell also said Mateen was speaking to someone on the phone in Arabic and was walking around the store texting.

Mateen is of Afghan descent, where the official languages are Pashto and Dari. It is not clear how Abell's staff deduced he was speaking Arabic.

He added that staff were on high alert since authorities has recently warned them to look out for suspicious activity in the area.

Abell did not specify which authorities gave this warning.

Port St Lucie police said they did not receive a report about Mateen's suspicious behavior.

The FBI has yet to comment.

Once it emerged that Mateen was the perpetrator of the worst mass shooting in history, Abell said, Lotus staff instantly recognized him and reported their experience to the FBI.

Omar Mateen, 29, (left) killed 49 people and wounded more than 50 others in the mass shooting in Orlando last week. Lotus Gunworks' owner Robbie Abell (right) reported Mateen to the FBI weeks earlier, he claims

Investigators outside the Pulse nightclub in Orlando, where Omar Mateen killed and wounded his victims

He added that he was glad they did what they could to block him.

'If something is suspicious, it’s our discretion. We are the gatekeeper,' Abell told the Journal.

Mateen bought his murder weapons from St Lucie Shooting Center days before his attack.

Ed Henson, the reitred NYPD officer who owns St Lucie Shooting Center, defended himself in the wake of the massacre saying, 'I don't make the laws.'

He insisted he put Mateen through the necessary background checks before selling him an AR-15 and a semiautomatic pistol.

Detectives have also been investigating whether there were explosives at the scene after witnesses said Mateen threatened to rig himself and his hostages with bombs.



