WASHINGTON, United States (AFP) — A Mississippi man said Thursday he alerted the FBI last year after spotting a chilling YouTube comment by a user with the same name as the suspect in the Florida school massacre.

The message — “I’m going to be a professional school shooter” — was posted under the name Nikolas Cruz.

The suspect in Wednesday’s deadly assault at a high school in Parkland, Florida is 19-year-old Nikolas Cruz, who has been charged with 17 counts of premeditated murder.

“When I saw the comment come through my push notifications and YouTube studio, it caught my attention. So I screenshotted it so I can share it with the FBI,” frequent YouTube user Ben Bennight told CNN.

The Federal Bureau of Investigation confirmed that in September 2017 it received information about the comment left on YouTube.

“The FBI conducted database reviews and other checks, but was unable to further identify the person who posted the comment,” the agency said in a statement.

Bennight told BuzzFeed News that the morning after he reached the FBI, agents came to his office and asked if he had any more information about the person who left the comment.

“I didn’t. They took a copy of the screenshot and that was the last I heard from them,” he told BuzzFeed.

President Donald Trump earlier tweeted that there were “so many signs that the Florida shooter was mentally disturbed, even expelled from school for bad and erratic behaviour. Neighbours and classmates knew he was a big problem. Must always report such instances to authorities, again and again!”