A Missouri teenager who survived 45 minutes without a heartbeat after being submerged in an icy lake headed home from the hospital on Wednesday, a miraculous recovery that has doctors stumped.

"I knew there were a lot of people in my corner praying for me," John Smith, 14, told KSDK nearly three weeks after his near-death experience.

Smith, of St. Charles, and two friends were walking across thin ice on Lake St. Louise on Jan. 19 when they all fell through, KSDK reported. One teen was able to swim to shore and rescuers saved another. But Smith could not immediately be found.

He was pulled from the bottom of the lake 15 minutes later with no pulse. Paramedics administered CPR for another 15 minutes until he arrived at SSM St. Joseph Hospital West.

Still with no pulse and a body temperature of 88 degrees, doctors continued CPR for 27 more minutes until he finally came to. It wasn't until the eighth-grader's mother entered the room and began praying that his heart began to beat, Dr. Kent Sutterer told KSDK.

Sutterer wasn't hopeful about the teen's chances of survival, partly because of his severely low body temperature. But not only is Smith alive, he survived without any brain damage. Now doctors are considering if the lake's icy temperatures had anything to do with preserving his brain function by chilling his body.

"The only factors medically that were really in John's favor is that this was a cold water drowning," Dr. Jeremy Garrett, a pediatric intensivist at SSM Cardinal Glennon hospital, told KSDK.

However, "this really shouldn't have worked in John's case," Garrett said. For one thing, the water in the lake was only 40 degrees so it wasn't cold enough to medically benefit Smith.

"Usually you'd like it to be colder," Garrett said, "and you'd like the victim to be smaller actually because what you really need to have happen is for the brain to get cold before the blood flow stops to the brain."

There's also the fact that his body temperature wasn't lowered in a controlled setting, Garrett said, making his recovery more miraculous.

While doctors remain baffled, Smith's family says his survival is the result of their prayers.