An Orlando gun store owner says that he warned the FBI about radicalized Muslim Omar Mateen just five weeks before the devastating attack on a gay nightclub that left 49 innocent people dead and 53 injured. Despite the multiple red flags surrounding Mateen, including ones that had prompted two previous FBI investigations, the bureau failed to respond to the gun store owner's alleged warnings.

According to Robbie Abell, co-owner of Lotus Gunworks, Mateen came into his store in May and asked to purchase law enforcement-grade body armor and bulk ammunition. Noting his suspicious requests and troubling behavior, Abell refused to sell him the ammo (they carry no body armor) and quickly reported Mateen to the FBI.

"The questions he was asking were not the normal questions a normal person would be asking," Abell told the Wall Street Journal, adding, "He just seemed very odd."

Abell noted that Mateen was walking around the store texting and at one point spoke in Arabic to someone on his phone.

His staff, he explained, had recently been alerted by authorities to watch for suspicious behavior in the area.

"Port St Lucie police said they did not receive a report about Mateen’s suspicious behavior," reports the Daily Mail. "The FBI has yet to comment."

The new report follows Disney's claim that they also warned the FBI about Mateen in April, when he appeared to be casing the park as a possible target. According to Mateen's wife, Noor Salman, he returned to Downtown Disney to scope it out during Gay Days (June 1-6). Salman is currently being investigated for her role in the terrorist attack.

Despite the multiple warnings, FBI Director Jim Comey has defended his bureau, insisting that they did everything they could in their investigations into Mateen, whom they interrogated three times in previous years.

"We’re going to look hard at our own work to see whether there is something we should have done differently," Comey told reporters Monday. "So far, the honest answer is, I don’t think so. I don’t see anything, in reviewing our work, that our agents should have done differently."

Time provides some more details about the FBI's investigations into Mateen:

Mateen first came to the FBI’s attention in 2013, when he was a security guard and co-workers heard him say he had connections to al Qaeda and Hezbollah, and that he hoped to martyr himself in a confrontation with the law, according to Comey. The FBI opened a preliminary investigation, which allows agents to conduct limited surveillance and searches, but not to use its most aggressive tools (like FISA or Title III warrants). The bureau used that power to run undercover agents against Mateen, search his “transactional records,” and record his conversations, Comey said. …

Preliminary investigations of terrorist suspects can run for six months in search of evidence the person is a member of a terrorist group or is planning a specific terrorist attack. The agent on the case can get a six-month extension if he or she thinks there might be more to find. And if there’s an indication the suspect really is planning an attack, the probe can be converted to a full investigation. In Mateen’s case, the FBI got one extension of the preliminary investigation, then closed the case after a total of ten months.

Two months later, however, Mateen’s name surfaced again, this time as an associate of an American who had gone to Syria and become a suicide bomber for an al Qaeda affiliate there. According to Comey, the two had known each other because they attended the same mosque, “but our investigation turned up no ties of any consequence between the two of them.”

Mateen eventually obtained his rifle from St Lucie Shooting Center, owned by Ed Henson, who defended their decision to sell him weapons after conducting the required background check. Here's Henson (via Daily Mail):

H/t The Right Scoop.