..."When you have the Internet and when you have so much communication these days, it's hard to distinguish between someone who's simply expressing their opinions about things and someone who may be troubled or someone who may be a real threat," he says.
For nearly 100 years, the Anti-Defamation League has been tracking groups that spout bigotry and hatred, often with more leeway to gather and file away information than law enforcement has.
"A lot of times we have information about a group because we've been reading their newspapers or looking at their websites or taking notes at their public rallies and that's perfectly constitutional activity," says Steve Freeman, the ADL's legal director. "And it's activity that enables us to basically function like an investigative journalist."
The ADL shares its findings with police or the FBI as the situation warrants.
The line is blurry, Freeman says, but he points to an example where doctors who perform abortions were targeted on "wanted" posters, their names blocked with an X if they had been killed.
"And that was construed as a true threat to the health and the life of the other doctors on the list, so it was more than just an expression," he says. "It was actually a threat."
What worries researchers and police the most are lone wolves — people who operate on the fringes of extremist groups — because their actions can be unpredictable.
"This man was like thousands of others on the white supremacist scene," Potok says. "He talked a lot about his enemies, he was full of anger, but he never to our knowledge crossed the line to criminal activity until this moment." ....NPR