U.S. investigators searching for the remains of two CIA pilots killed in a plane crash 50 years ago in China's northeast said Monday they found wreckage but no bodies. 

An aging witness led the U.S. Army team to a crash site, and officials planned to test debris found there to see if it was from the C-47 that was shot down on Nov. 29, 1952, during a mission to pick up an anti-communist Chinese agent. 

Team members said they would take the debris and photos and measurements of the site back to the United States for study, and decide later whether to continue the search in China. 

"We will need more investigation," said Aaron Lehl, a civilian analyst for the eight-member team from the U.S. Army's Central Identification Laboratory in Hawaii. 

Lehl said he knew of no other American planes missing in that hilly, wooded area. So if the debris is shown to be U.S.-made aircraft parts, "then we are very hopeful that this is the aircraft that went down on that evening," he said at a news conference at the U.S. Embassy in Beijing. 

The team searched for shallow graves where a 78-year-old Chinese villager said he helped to bury the badly burned bodies of the pilots near the crash site, but "we did not find any remains," said Franklin Damann, an anthropologist. 

The CIA plane was shot down near the North Korean border in the region formerly known as Manchuria. Its pilots — Robert C. Snoddy of Eugene, Ore., and Norman A. Schwartz of Louisville, Ky. — were killed and two CIA officers aboard who survived the crash were captured and spent two decades in Chinese prisons. 

John T. Downey of Connecticut and Richard G. Fecteau were held until President Nixon publicly acknowledged they were CIA officers. 

Chinese and U.S. forces were fighting on opposing sides in the Korean War, and the CIA was trying to undermine the fledgling Chinese communist government. 

The CIA plane took off from an airfield near Seoul, South Korea, and had dropped "extraction equipment" — poles that the plane would use to pick up the Chinese agent, Lehl said. He said the plane circled for about 45 minutes and was coming in for the agent when Chinese forces hit it with .50-caliber machine gun fire. 

Lehl said he didn't have any information about the identity or fate of the Chinese agent. 

The U.S. team began their search early last week and worked through the weekend. They were guided to the site by the villager who they said was the last survivor of a group that arrived about six hours after the crash and buried the pilots' bodies. 

The team had to cross a rushing, rain-swollen stream using a sling chair strung on a cable set up by Chinese authorities. They said the Chinese farmer was too frail to cross the stream, but was close enough to point out the crash site. 

"We did find ... a nice tight pocket of 20 [to] 30 meters of aircraft wreckage," said Damann. 

The team used metal detectors to search a 300-square-foot area and dug test pits looking for debris, he said. 

Damann said none of the items found bore any serial numbers that would confirm it was from a C-47 or markings from the aircraft manufacturer, McDonnell Douglas. 

China's agreement to let the U.S. Defense Department to search the site was the first time that Beijing has cooperated on a search for the remains of Americans who died in China during the Cold War. 

Foreign Ministry spokesman Liu Jianchao said this month that China decided to permit the search to promote "friendship between the two peoples and in a humanitarian spirit." 

The Pentagon and advocates for the missing hope that China will provide more information about the fate of others, including U.S. soldiers captured by Chinese troops during the 1950-53 Korean War. An estimated 8,100 U.S. servicemen are missing from that war. 

About 20 Americans who disappeared in China during the Cold War are still missing, according to Benjamin Wong, a member of the search team and an official of the Pentagon's office for prisoners of war and soldiers missing in action.