'Think before you post': FBI issues warning about posting on social media

'Think before you post' -- that's the new message straight from the FBI. They warning what can happen if you fire off a fast and furious post.

The FBI is making an example of a college student who posted a message threatening mass violence at a Chicago campus. He deleted it almost immediately, but first someone spotted that post and it triggered a frantic and fearful response.

Jabari Dean says he was angry, then took his rage about the Laquan McDonald police shooting and turned to social media to threaten the University of Chicago.

Authorities say Dean posted his threat in November 2015 writing, "I will execute approximately 16 white male students and or staff, which is the same number of times McDonald was (shot). I then will die killing any number of white policemen in the process. This is not a joke."

"People took it as a terrorist threat. The University got shut down. I got arrested by the FBI and now I don't know what my future looks like,” Dean said.

Now Dean stars in this new public service announcement from the FBI, warning others to think before they post.

“I was just really sorry, that's the first and foremost thing. I was incredibly, really sorry. I did not mean for that to happen,” Dean said.

Dean has become the FBI’s poster boy of what not to do as part of his community service deal to avoid prison.

Special agent-in-charge Michael Anderson says they've seen an increase in online threats.

“They have keyboard courage, they're having an bad day or having an emotional moment, and they send that out there and they got to understand it's out there for the world and in that world is law enforcement and we have a duty and obligation to respond rapidly,” Anderson said.

Dean’s threat shut down U-of-C and led to a massive response from law enforcement.

“If we're responding to a non-event at the University of Chicago, then we're not able to respond to an actual event someplace else,” Anderson said.

Agent Anderson says they could have sent Jabari Dean to prison, but decided he was much more valuable as a tool to convince others to think before posting.