Chris Benoit may have been so depressed that he believed his family would be “better off in heaven” when he allegedly murdered his wife and son before killing himself, says an expert on murder-suicide.

WWE wrestler Benoit, his wife Nancy and son Daniel, 7, were found dead Monday in their suburban Atlanta home.

Local police are treating the case as a murder-suicide.

Dr. John Bradford, associate chief of the integrated forensic program for the Royal Ottawa Health Care Group, said murder-suicides that wipe out a family are most often carried out by the father.

“The most usual cause is a major depression, normally a severe one with psychotic features,” said Bradford, also a professor of forensic psychiatry at the University of Ottawa.

“They sort of start to think, in this psychotic thinking, that the whole family would be better off in heaven ... that, ‘This is a horrible place, I think we’d all be better off dead.’”

Psychiatrists commonly refer to murder-suicide as “extended suicide,” when the killer decides life is not worth living, he said.

Police in Georgia say they will be investigating whether steroid use was a factor in the case.

Prescription anabolic steroids were found in the home.

Bradford said steroid use carries “a lot of baggage” when it comes to psychiatric health because the drugs alter brain and body chemistry.

“People that abuse steroids carry with them an increase risk of rage and rage attacks. There’s also an increased risk of depression, so it’s kind of a double whammy.”

Dads who decide to kill their kids often turn to methods such as smothering because they don’t want the children to suffer, said Bradford.