SAN FRANCISCO (KGO) -- Accused Florida school shooter Nikolas Cruz had posted on social media about his inclination toward violence -- and it's raising questions about who should be held accountable for preventing such tragedies when threats are posted online.
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"In 2017 the FBI received information about a comment made on a YouTube channel," FBI Special Agent in Charge Robert Lasky told reporters in Florida. "The comment simply said, 'I'm going to be a professional school shooter.'"
Lasky said the FBI investigated, and even paid a visit to the man who reported the comment.
"The local agents came to my house and asked me for more information," Ben Bennight told local TV station WLOX in Biloxi, Mississippi. "All I had was the screenshot and the name."
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Only later did investigators learn that the screen name belonged to Nikolas Cruz, when they discovered his Instagram account -- which showed a fascination with guns and knives.
"He said, 'Well, it's the same name, and we think it might be the same person,'" Bennight said.
When it comes to investigating suspected mass shooters online, it seems hindsight is 20/20, said tech and policy writer Greg Farenstein.
"These days there's a lot of first indicators before people cause harm to others," he said, adding that the problem is finding those indicators early enough. "A large percentage of the entire world is on these platforms and combing through all that data is an enormous challenge."
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Equally challenging is deciding what to do after finding an apparent threat -- especially amid concerns over free speech. Companies like Facebook and Google have historically been loath to remove or investigate questionable posts, but Farenstein says that's starting to change.
"If they think there is a threat, they're more likely to report it to the authorities and work with law enforcement to prevent a tragedy," he said.
The ethical question is complex and nuanced, but internet law attorney Bradley Shear says the legal question is actually quite simple. It goes back to what he calls one of the building blocks of the internet: Section 230 of the Communications Decency Act.
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"It basically lets digital platforms off the hook from investigating certain issues," he explained.
Shear said courts have repeatedly ruled that companies like Facebook and Google are not to blame in tragedies like the one in Florida -- even when it's later found the suspected shooters posted warnings online. In fact, when a threat is uncovered, Shear said, police often can't do anything unless there's clear evidence of imminent danger.
"To say, you know, this person is definitely going to kill somebody, hurt somebody, we just don't know that from simple comments (on a social media post) in general," he said.
In response to requests for comment on the shooting, Facebook issued a statement that reads, in part: "This is a terrible tragedy, and our hearts go out to the people who have been affected. There is absolutely no place on our platforms for people who commit such horrendous acts. ... We have found and immediately deleted the shooter's accounts on Facebook and Instagram."
Click here for full coverage on the Parkland, Florida school shooting.
Florida shooting could re-ignite debate over threats posted on social media
PARKLAND SCHOOL SHOOTING