There were signs.

Nikolas Cruz, the 19 year old who walked into Marjory Stoneman Douglas High School, in Parkland, Florida and opened fire, killing 17, had caught the attention of teachers and authorities, already.

He was troubled.

According to Buzzfeed News, there were red flags from other sources, as well.

 Last fall, a Mississippi bail bondsman and frequent YouTube vlogger noticed an alarming comment left on one of his videos. “I’m going to be a professional school shooter,” said a user named Nikolas Cruz.

The YouTuber, 36-year-old Ben Bennight, alerted the FBI, emailing a screenshot of the comment to the bureau’s tips account. He also flagged the comment to YouTube, which removed it from the video.

I’d like to think YouTube did more than just remove the comment. In this situation, they should have contacted authorities, as well.

FBI field agents with the Mississippi office contacted Bennight “immediately.” On September 25 they conducted an in-person interview, to inquire about what he knew about this user, Nikolas Cruz, and the comment he’d made.

“They came to my office the next morning and asked me if I knew anything about the person,” Bennight told BuzzFeed News. “I didn’t. They took a copy of the screenshot and that was the last I heard from them.”

After Wednesday’s shooting, they reached out to him again.

So what were the signs that people noticed about Cruz that caused concerns?

According to classmates, teachers, neighbors and family members, he was a “loner.” He was obsessed with guns and often flaunted his weapons on social media.

The school had previously flagged Cruz as a potential threat.

He’d been expelled, and school officials were warned not to allow him on the campus with a backpack.

There were so many signs, and people had real concerns, but no action was taken.

Now the question that should be debated is what could they have done? How could this tragedy have been averted?

The FBI began following up on the information they had, immediately.

To date, it’s not known if they have confirmed that the “Nikolas Cruz” from the deleted YouTube comment was the same Cruz from Wednesday’s shooting (I’m thinking it’s a safe bet, yes).

But around 4:30 p.m. on Wednesday — about 30 minutes after Cruz was taken into custody by police in Broward County — Special Agent Ryan Furr with the FBI’s Miami field office called Bennight and left him a voicemail.

“I think we spoke with you in the past about a complaint that you made about someone making a comment on your YouTube channel,” the agent said in the message, which Bennight provided to BuzzFeed News. “I just wanted to follow up with you on that and ask you a question with something that’s come up, if you wouldn’t mind giving me a ring.”

Something that’s come up.

Agents from the Mississippi field office paid Ben Bennight another visit.

“They asked me if I knew who he was. I didn’t. I don’t,” Bennight said. “Then they left.”

According to Buzzfeed News, the YouTube account of the Nikolas Cruz who commented on Bennight’s video was still active Wednesday evening, but has now been removed, for what YouTube lists as, “multiple or severe violations of YouTube’s policy on violence.”

There were signs. These are not uncommon among these mass shooters.

Where do we go now, with the knowledge we have?