Steve Fossett vanished more than a year ago, and until this week, no trace of him had been found.
According to a spokesman for the Federal Aviation Administration, the information on the recovered items -- including Fossett's name, address and date of birth -- all match the agency's records.
"They have authenticated two of the documents. They are a pilot's license and one is a ... National Aeronautic Association card. These did belong to Steven," said Sheriff John Anderson, Madera County.
Three ID cards are three pieces of a puzzle that could help unravel the mystery behind Steve Fossett's disappearance.
"I was just off on a day hike. For the local people around here, I was going up the Minaret Trail to go find Minaret Mine -- or going up to Minaret Mine and check out the mines. It was kind of too late in the day for me to make it to the mines," said Preston Morrow, the hiker who found Steve Fossett's items.
Morrow was hiking in the rugged mountains near Mammoth Lakes, California, on Monday when he found the items that possibly belonged to the pilot.
"Based on the identification that we have looked at, they feel that there is enough to at least go out and do a search of the area for any wreckage," said Lieutenant Jim Short, Mammoth Lakes Police Department.
The hiker also found about a thousand dollars in cash and a sweatshirt. However, there were no remains or wreckage.
"When, I saw the money, I thought, 'Oh my gosh! Hundred dollar bills ... that's crazy!' And, that probably was my first thought, 'Wow! Hundred dollar bills.' When I saw the name, it didn't register that afternoon," said Morrow.
After Morrow told someone at work about his find, he realized who the items belonged to and turned them into police on Wednesday.
Fossett was declared legally dead in February after an unsuccessful search that covered 20,000 square miles. He vanished more than a year ago after flying from a ranch 80 miles south of Reno. The ranch was owned by hotel mogul Barron Hilton.
Fossett was inducted into the Aviation Hall of Fame last year. He was the first man to travel around the world alone in a balloon. Fossett also swam across the English Channel, competed in Alaskan dog races and climbed Mount Kilimanjaro.
The ID was found about 60 miles outside the search area near Mammoth Lakes. The sheriff's department is now coordinating a flyover of the area and sending search and rescue teams into the rugged mountains on foot.
In a statement released a few hours ago, Steve Fossett's widow, Peggy Fossett said: "I am aware of the search underway for my husband in the Mammoth Lakes area ... I am hopeful that this search will locate the crash site and my husband's remains. I am grateful to all of those involved in this effort."
The Madera County Sheriff's Department has already established a command center in Mammoth Lakes.
The search began at around 11 a.m. on Wednesday and involved a helicopter and crews on foot. The mountains in the area have an elevation of about 13,000 feet.
"You would think if they could find documents this small, that they could certainly find an aircraft. So, I guess that's the mystery," said Anderson.
Authorities were announcing their plans for the search come nightfall on Wednesday. A larger search is planned for Thursday morning. Eyewitness News reporters Robert Holguin and Rob McMillan contributed to this report.