(CNN) -- A decaying address book. A black plastic comb. A dirty penny.These are some of the last things a young World War II airman put in his pockets on the day he died six decades ago. And they are a few of the many clues beginning to emerge in the search for his identity.The investigation began in earnest two weeks ago, when climbers found a frozen body in a U.S. military uniform at the bottom of a glacier in the Sierra Nevada. Forensic scientists exhumed the body from its icy tomb and transported it to Honolulu, Hawaii, where the body is being studied at the Joint POW/MIA Accounting Command, the largest forensic crime lab in the world.So far, investigators have narrowed the body's identity to one of 10 World War II soldiers, out of the thousands who are missing or unidentified.Forensic scientists at the lab believe the airman was Caucasian, had fair hair and was probably in his early 20s when he died, judging by his teeth."These root tips are closed, which is indicative of someone at least 21 years old," said Dr. Andy Henry, a forensic dentist.From looking at the airman's bones, scientists think he most likely died when his plane crashed six decades ago, not by freezing to death in the mountains."The injuries are so substantial, he didn't feel anything. He died immediately," said Dr. Robert Mann, a forensic anthropologist.Investigators are trying to move beyond these general observations to pinpoint the airman's precise identity. Here are some of the clues they used to narrow their search from thousands of missing soldiers to just 10, and are continuing to employ to find his identity:• He was wearing a World War II Army Air Force uniform.• A corroded nameplate, collar pin and Army Air Corps insignia were found on his uniform.• Remnants of his sweater, undergarments and socks are intact.• He had a broken plastic black comb.• Dimes from 1936 to 1942 were found in his pocket.Some potentially vital clues, such as three small leather-bound address books, haven't yielded as much information as investigators had hoped.The pages of the books, which may once have contained the names, addresses and phone numbers of friends and family, were too decomposed to reveal their original content.Scientists are convinced that with the help of DNA testing they will be able to identify the airman in the weeks and months ahead.In Pleasant Grove, Ohio, three sisters, all in their 80s, hope the frozen airman is their big brother, Glenn Munn, whose plane went missing in the Sierra Nevada in 1942."I just wanted a final confirmation to know he was found and have him brought home here for burial," says Sara Zeyer, Munn's sister. "We don't know that though. We don't, but that's my wish."