CINCINNATI -- The arrest of a suspect in the national mail bomb case eased the anxiety for many Americans who worried that they could be next target, but violence isn't new in U.S. political history.
Xavier University political scientist Sean Comer said the case of Cesar Sayoc Jr. isn't the first and won't be the last.
"The most obvious example, and the worst, is the Civil War," Comer said. "But the unrest in the '60s, the civil rights movement, you've had members of Congress who were nearly beaten to death on the floor and presidents being shot, so violence has always been part of our history."
So when does someone cross the line from civil discourse to violence?
"When people feel like they have no more control and there's absolutely nothing they can do to talk to or deal with the other side, I think that's a lot of time when you see people resort to violence," Comer said. "When they feel like the system is broken."
The current political climate already existed before Donald Trump was elected president, but he's raised it to another level, according to Comer.
"We're at a point right now where people not only feel that the other side is wrong, but they're evil, and that is a real challenge for democracy to deal with," he said.
So how can the current climate be taken down a notch? Comer said it starts in local communities.
"It's also incumbent upon our elected leaders to step up and say, 'We're going to work together, we're going to work across the aisle,' because otherwise we're locked in this battle and it's only about campaigning, and when it's only about campaigning people feel like they've lost control," Comer said.
Violence puts our democracy in a very scary place, Comer said.
As for Sayoc, he's facing as much as 58 years in prison for charges of illegally mailing explosives, illegally transporting explosives across state lines, making threats against former presidents, assaulting federal officers and threatening interstate commerce.
Authorities said Sayoc, 56, sent at least 13 explosive devices to prominent Democrats including former President Barack Obama, former Vice President Joe Biden and former Secretary of State and 2016 presidential nominee Hillary Clinton.
He has a criminal history that includes allegations of larceny, theft, battery and possession of controlled substances. The most serious previous charge came in 2002, when police said he threatened to blow up a Florida Power and Light facility.
Cincinnati psychologist Dr. Ken Manges said Sayoc was likely "delusional." He said he believes Sayoc was trying to emulate the president, noting that his van was covered in pro-Trump stickers.
"He has a sense of inadequacy and loneliness," Kanges said. "He has a belief that he can acquire fame and be remembered. He would like to be thought of as worthy and hope to be congratulated by the person he's trying to emulate."