LIVERPOOL, N.Y. -- James and Mary Proper lived and died together in their home. Neighbors describe the couple as extremely close.

"He was the caretaker of the bunch. I know that she was ill for the past couple of years or so," said Scot Walpole.

Which is why neighbors think Mary, who was 86, went first. But they were surprised to learn James, 84, died as well.

"He was a very spry man. He would go out and snow blow and do the gardening and things like that," said Walpole.

The Onondaga County Sheriff said they died of natural causes, and it appears to have happened same day.

Psychologists have studied why an elderly person will die within minutes, days, or weeks of his or her spouse. Some say, it's the result of a broken heart. But most agree it's purely coincidence.

"It could be due to the fact that they're about the same age, in their 70s or 80s so there could be an overall effect of aging," Syracuse University psychology professor Dr. William Hoyer said.

Dr. Hoyer sites a 1981 study that found the timing of death between spouses is linked one percent of the time.

"Many times, people suffer that bereavement and then go on to live a longer, healthier life even with this loss of partner," said Dr. Hoyer.

But this could have been that one percent of the time when a spouse can't go on without his life partner.