Why do parents kill?

In the meantime, police, school officials and residents of northeastern Berks County are grappling with a more immediate question: Why?

Dr. Phillip Resnick, a professor of psychiatry at Case Western Reserve University in Cleveland, has spent a career studying parents who kill their children. The motivations fall into several general categories, according to Resnick, who said he could not speak to the specifics of Snyder’s case.

Some parents kill from altruistic motives, however skewed — the sense that a child would be better off dead than alive, Resnick said. Others want to get rid of unwanted children. Some are acutely psychotic and lose touch with reality. Others kill accidentally through child abuse or act out of revenge — a desire to see a romantic partner suffer the loss of their children.

“Was she overwhelmed? Was she depressed? Did she have any psychotic thoughts about the children, or were they simply in the way for her?” Resnick asked.

On the evening of the hangings, Snyder told rescue workers that Conner was bullied and had been threatening suicide, according to 911 recordings. She reported Conner killed his sister because he “didn’t want to go alone” — a claim she continued to make when police arrested her Monday at her home on Route 143, according to Adams.

But authorities have said their investigation uncovered no evidence Conner was picked on at school, and they have described him as seemingly happy.

Resnick, a nationally recognized expert on filicide, said his research suggests hanging is a “very unusual method” for a parent to kill a child.

“I don’t remember if I’ve ever seen a case, especially a double-hanging,” said Resnick.

Jack Levin, a criminologist at Northeastern University in Boston who studies family murder, called the allegations against Snyder “strange in so many respects” and said it is difficult to develop of likely profile of her as a result.

“The fact that it is a woman who kills her children by hanging is something you just don’t see,” Levin said. “I’ve studied family annihilation for three decades, and I’ve never run across something like that.”