Nikolas Cruz's threats to shoot up school were enough warning to act, legal experts say

Before he shot and killed 17 people at a Florida high school last week, Nikolas Cruz posted disturbing and threatening messages on the internet.

Two years ago, he said he looked forward to turning 18 so he could buy a gun and shoot his peers at school.

Last fall, a YouTube comment posted by someone with the same name said: “I’m going to be a professional school shooter.”

And there were the photos Cruz uploaded to Instagram of guns and knives.

So why didn't authorities and those social media platforms do more to investigate someone who by all accounts was a ticking time bomb? A digital-crimes scholar and a free-speech expert both told USA TODAY NETWORK-Wisconsin that officials have the ability to take measures to step in before threatening online behavior leads to carnage.

In Cruz's case, that apparently didn't happen. A neighbor had reported Cruz’s 2016 posting about his desire to shoot up his school, but a police officer dismissed that concern and said there was nothing authorities could do, according to the Wall Street Journal.

Drexel University associate professor Rob D’Ovidio, who studies crime and technology, said law enforcement could have intervened.

“Most certainly the police could have taken action,” D’Ovidio said.

RELATED: Wisconsin AG Brad Schimel says he'd train gun-carrying teachers if state law allowed it

RELATED: Wisconsin terror threat law, digital surveillance used in efforts to thwart school threats

At minimum, D’Ovidio said, Cruz's comments should have prompted an investigation to understand the nature of the threat and who was behind it.

D’Ovidio said social media companies also need to be more diligent at detecting and reporting to law enforcement content that raises the potential for violence and other criminal activities.

“YouTube. Instagram. Twitter. There’s a role that they can play and there’s a responsibility they have,” D’Ovidio said. “It might not be a legal responsibility, but it’s a moral and societal responsibility.”

Schools also may take action when students threaten violence on social media.

Educators and police are free to review any material posted publicly, as there would be no reasonable expectation of privacy for such content, said University of Florida professor Frank LoMonte, an expert in First Amendment law and student speech rights.

Authorities also are free to ask someone whether his or her social media postings may indicate some sort of distress.

Legal issues begin to arise when officials punish students for speech that is not a clear or serious threat. Authorities should always investigate when there is a credible potential for violence. At times, mental health counseling may be a more appropriate tool than defaulting straight to expulsion, LoMonte said.

“Where the constitutional questions get tricky is when the school decides to suspend or expel a student for words or images that ambiguously, or perhaps jokingly, refer to violence without any proof of an intent to actually behave violently,” LoMonte said.

However, LoMonte said there is a growing consensus in the law that if a student posts anything even hinting at the possibility of violence against peers or staff in a school, that material is not protected and can be punished.

And that’s true even if the student posted the material off campus, outside of school hours and claimed he or she did not actually intend to carry out the act, LoMonte said.

"I think the prevailing view of every court is that if you make a concrete reference to violence, particularly one with a time and a place, that you’ve overstepped the First Amendment," LoMonte said.