The autopsy showed the nine-year-old boy died of hypothermia, and his death has been ruled accidental, said Gary Mello, a spokesman for the Bristol County district attorney's office.
Corey, who had attention deficit disorder, vanished last Thursday while looking for his dog, Jasmine, during a sudden nor'easter that piled heavy snow on the region. The dog later showed up at a neighbor's house.
For nearly three days, hundreds of searchers combed woods, marshes and streams near the boy's home.
On Monday, his father, Peter Anderson, thanked the searchers who helped look for his son and did "everything that could be done to find Corey as quickly as possible."
The rescue crews "searched for our son as if they were searching for their own," he said.
Grief counselors were on hand at the Nourse School, Corey's elementary school. Principal Gerald Smith said his classmates had a lot of questions about how Corey died and why it took so long to find him. Smith said they were assured that what happened to Corey wouldn't happen to them.
The boy's body was found Sunday near a creek just 300 yards from his home. A search party discovered him curled up in a ball 15 feet away from the water, on the bank of Mulberry Brook, reports CBS News Correspondent Kristin Jeannette-Meyers.
"There was an outcropping of trees in the swamp, and he was lying on his left side in an outcropping, trying to get out of the water, trying to stay dry," said State Police Sgt. Paul Hartley. "For an adult to get to that area, you'd have to crawl on your hands and knees."
Divers had passed the spot several times but missed Corey. Perhaps, they said, he was covered by snow that has since begun melting under the New England rain.
The search for the fourth-grader had captured national attention, with hundreds of rescuers searching on land, underwater and in the air.
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