Any time there’s a violent tragedy—the killing of at least 86 people at a youth camp in Norway, the shootings of a congresswoman and others in Tucson, the Virginia Tech massacre—one question seems to ring clearer than others: Why didn’t someone notice beforehand that the suspect might be disturbed and capable of committing deadly violence?

Psychiatrists and mental health experts say there are some clear warning signs that a person could be suffering a mental breakdown and needs help.

“The road to the crisis is often long, and there are a lot of signposts,” said Bryan Gibb, director of public education for the National Council for Community Behavioral Healthcare. “It’s our job to educate people about those warning signs so people can get the treatment they need early.”

But the experts also warn that a breakdown rarely leads to violence. “It’s the rare person who has an extreme form of behavior that becomes either violent or self-injurious,” said Dr. Thomas Wise, a professor in the psychiatry and behavioral sciences department of Johns Hopkins Medicine in Baltimore and chairman of behavioral health services for Inova Health Systems in Fairfax, Va.

People prone to mass violence often have fallen victim to an “overvalued idea,” a psychiatric term for an unreasonable belief over which the person has become obsessed, Wise said.

Overvalued ideas are not delusions, in that people with overvalued ideas are not completely and irrationally fixed in their beliefs despite any evidence provided them, he explained. The irony is that people suffering from delusions and clearly mentally ill, he said, are less likely to commit violence than people teetering on the brink of obsession who are not technically suffering from a mental disorder.