Jack Levin, a criminologist at Northeastern University, said men who kill their families are usually in their 30s or 40s and suffer from chronic depression that has developed over years.

“Most of the time, we’re talking about a middle-aged guy who is not doing well at the very time in his life when he feels he should be reaching the pinnacle of success,” Levin said. “Instead, he’s sliding downhill fast.”

He said the Deep Creek murder-suicide can be considered a mass killing , which involves four or more people.

He estimated there are about 20 mass killings in the U.S. annually. About 40 percent of them are familicides, Levin said.

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