Early Thursday morning, Myron May opened fire at a Florida State University library, wounding three and leaving a college community shaken.

It’s not yet known why the 31-year-old Florida State alumnus decided to act out, or why he targeted the Strozier Library. But May, who was killed by police in a shootout, left behind a trail that indicates an apparent struggle with mental illness.

“Mr. May had a written journal, and videos, where he expressed fears of being targeted, and he wanted to bring attention to this issue, of targeting,” Tallahassee Police Chief Michael DeLeo said at a news conference Thursday. “A preliminary review of these documents and videos demonstrate that Mr. May was in a state of crisis.”

For those who watched the Florida State shooting play out online or on TV, it might have been easy to simply link mental illness and violence. But is that a fair connection to make?

Jeffrey Swanson, a professor of psychiatry and behavioral sciences at Duke University, studies these kinds of issues. You might have heard his name after the Sandy Hook Elementary School shooting, for example, or after Elliot Rodger’s shooting spree in California.

“We’re talking about two really important, really complicated, but different public health problems that intersect on their margin,” Swanson said. “Serious mental health illness is one, and gun violence … is another one. And they’re both big problems. But we tend to focus on this little intersection between the two.”

Thomas Insel, director of the National Institute of Mental Health, spoke on this topic at a forum this year. You can read about it in Psychiatric News.

In the weeks leading up to the Florida State shooting, there were signs that May might have suffered from mental or emotional issues. In October, for example, an ex-girlfriend called police in New Mexico, saying she was worried about his welfare. In September, an officer visited his apartment, and May told him he was hearing voices in the walls.

Those who knew May during his college days, and even before then, in his youth, remember a funny and bright person who was a kind and decent friend. Many expressed shock this week, when they learned that May had been involved in the shooting.

“His intelligence was the first thing that struck me and also how comfortable he was around people,” said Erick Tyrone, a friend who knew May from the National Black Law Student’s Association. “We were both extroverts, and when we were in a room together it was like, together, we knew everybody.”

In addition the journals and videos, May also sent a series of packages to eight friends, according to reports. One package is headed to Joe Paul, of Virginia, who told an ABC affiliate in Atlanta that he’s been told to contact investigators when it arrives.

“What did he send everyone?” Paul told the Associated Press. “Was it a manifesto? Was it a message? I don’t know. I think I’m just as curious as everyone else.”