FBI was warned about alleged shooter nearly 5 months ago, tipster says

(CNN) The FBI was warned in September about a possible school shooting threat from a YouTube user with the same name as the suspect in Wednesday's campus massacre in Parkland, Florida , according to a video blogger.

Ben Bennight, the 36-year-old YouTube video blogger from Mississippi, noticed in September an alarming comment on a video he'd posted. He told CNN he immediately contacted the FBI.

"Im going to be a professional school shooter," read the comment, left by a user with the name Nikolas Cruz, the same name of the suspected shooter who opened fire at Marjory Stoneman Douglas High School on Wednesday, killing at least 17 people

A law enforcement official told CNN earlier Thursday the FBI had received two reports regarding potential threats from the shooter.

But later Thursday, a separate law enforcement official said authorities believe they only received one report, regarding the comment on YouTube. The investigation is in its early stages, the source said, and information could change as leads are investigated.

The FBI did not share the information with local law enforcement, the first official said.

Bennight emailed a screenshot of the comment, which he shared with CNN, to what he thought was an FBI tip line, but the email address was invalid, he said. Bennight said he followed up with a phone call to the FBI. The comment on YouTube has since been pulled down.

According to Bennight, agents from the FBI's field office in Mississippi contacted him and came to his office to conduct an in-person interview the next morning. Bennight told the agents he didn't know anything about the user, he told CNN.

That was the last contact he had with the FBI until Wednesday, he said.

The FBI special agent in charge of the Miami division, Robert Lasky, confirmed Thursday morning that the bureau received a tip last year about the YouTube comment.

"No other information was included with that comment which would indicate a time, location or the true identity of the person who made the comment," Lasky said during a news conference. "The FBI conducted database reviews, checks but was unable to further identify the person who actually made the comment."

On Wednesday afternoon, after Cruz was arrested, Bennight got a call from an agent in the FBI's Miami field office, who wanted to follow up on the September incident, he said. A few hours later, FBI agents from the Mississippi office paid Bennight another visit.

"I saw the story kind of go across my news feed, but I didn't pay a whole lot of attention to it," he recalled Thursday in a phone interview with CNN. "But when the FBI said it was the same name, the first thing that went through my mind was, 'Wow, I hope you were at least watching this guy that I alerted you to months ago.' "

"I think in today's online world, it is very difficult to narrow down who does what without more information," Bennight told CNN's Jake Tapper later Thursday, "and unfortunately, I wasn't able to provide them with much."

Noting that he doesn't know exactly what it takes for the FBI to investigate these sorts of tips, Bennight acknowledged that "had more time and effort been put into finding out who the username belongs to, ... they may have been able to find out who this person was and put him on their radar."

Update: This story has been updated to reflect new reporting regarding the number of alleged threat reports the FBI received about the shooter.