On New Year's Eve in 1980, a man named Wally Nelson stumbled across the body of his friend, lying in the snow just a few meters from his door.

Jean had returned to her parents' house after a night of partying. She wore a coat, mittens, and cowboy boots as she set out to seek her friend's help.

She lost consciousness after tripping. For six hours, she lay in the cold, warmth draining away to leave her frozen solid.

Nelson told Minnesota Public Radio that he grabbed her by the collar and dragged her into the porch.

I didn't think she was alive. A few bubbles came out of her nose, but it was stiff.

Nelson's prompt response may have saved Hilliard's life. Her story has become part of medical lore.

How could a body survive being frozen solid?

It's unusual for people to survive freezing temperatures, but it's not uncommon either. Medical specialists say that nobody is dead until it's warm and dead.

The realization that extreme cold isn't the end of a life is the basis of therapy. The body's appetite for oxygen can be reduced if the body's temperature is lowered.

In medical settings, or on rare occasions elsewhere, a chilled body can put the brakes on the dying process for a while.

The extreme nature of her condition stands out.

Her body temperature was a full 10 degrees below that of a healthy human. Her skin was too hard to be pierced with a hypodermic needle.

George Sather, the doctor who treated her, said that the body was cold and solid.

After just a few hours, his body was back to normal. She was discharged to live an unremarkable life after talking by noon and having little more than blisters on her toes.

It was thanks to the power of prayer that she was able to achieve it. Where does biology stand on the issue?

Water takes up more volume as a solid than it does as a liquid The expansion is bad news for body tissues that are caught in the cold, as they risk swelling andrupturing their containers.

Even a few stray ice crystals that bloom in the wrong place can pierce cell membranes with their needle-like shards, reducing the body to blackened patches of dead skin and muscle.

Animals have adapted to deal with the dangers of sharp, expanding ice crystals. A type of natural antifreeze can be found in deep-sea fish.

The wood frog is able to resist freezing and dehydration by flooding it's body with sugar. Outside of their cells, water can be used to make tissues look like frog shaped ice cubes.

It's difficult to say for sure how the body withstood being frozen. Her body chemistry was unique. Is that her make-up?

It might be possible. What does frozen mean in this case? The core body temperature was said to be still above freezing.

Muscular rigidity increases to such an extent that it can look like rigor mortis, the stiffening that happens to dead bodies.

She had a body that was cold and white and her eyes looked glassy. A body will look ashen if it closes off the blood vessels under the skin.

If medical staff are persistent enough to try using a smaller gauged hypodermic on heavily restricted veins, we might even imagine a bent needle or two.

With little to go on other than a few surprised accounts, we can only speculate on whether or not Hilliard's frozen body was typical, shocking, or oddly unique in its ability to survive such a drastic change of state. She was lucky.

The more we know about the amazing things the human body can do, the less we need to rely on good fortune to save lives like hers.