U.S. authorities are tracking a man whom they say is influencing Islamic State of Iraq and Syria (ISIS) followers from his home in Michigan -- using social media to inspire jihad.
Ahmad Musa Jibril is a Palestinian-American cleric whose extremist views caught the attention of U.S. law enforcement.
His alleged call for jihad in 2005 led federal prosecutors to describe him as a man who "encouraged his students to spread Islam by the sword, to wage a holy war" and "to hate and kill non-Muslims."
In 2012, Jibril was released from federal prison after serving six years for insurance fraud. He is currently living in Dearborn, Michigan, where he's on probation.
Even under law enforcement supervision, he's become one of the most influential figures for western foreign fighters, according to British researcher Peter Neumann.
"We counted all their likes, their mentions and their follows and what turned out to be true is that Ahmad Jibril was liked by an astonishing percentage of foreign fighters," Neumann says.
According to Neumann's research, 60 percent were following him on Facebook, favoriting his tweets and retweeting his messages.
Last year, a federal judge heavily restricted Jibril's ability to use social media. As a result, his accounts have gone dormant. And yet his Facebook page has grown from 211,000 likes last year to 245,000 today.
Jibril declined CBS News' requests for an interview. His probation ends in one month. Without new charges, he is free to go back online without restrictions.
He's toned down his rhetoric, suggesting maybe he's a changed man. Some aren't convinced.
"There is nothing to suggest he has changed his views," Neumann says. "He has toned them down because he realizes that if he doesn't tone them down they will come after him."
That is the dilemma law enforcement deals with everyday: How best to identify potential threats who may mask their true intent.
But social media can also help law enforcement with important clues about who and where extremists might be. That could escalate to monitoring emails, texts and phone conversations, all of that under court orders.
The FBI looks at hundreds of people who may have terrorist leanings and opens investigations into some of those cases. FBI Director James Comey confirmed Wednesday the bureau has now opened investigations in all 50 states.
Law enforcement has been very public about the damage they believe Edward Snowden caused to intelligence gathering in the U.S. by disclosing information about the NSA's surveillance program.
Director of National Intelligence James Clapper has said that Snowden caused a significant blow to national security by exposing and compromising intelligence gathering tactics.