WASHINGTON — When communist Chinese jets shot down an American surveillance aircraft 50 years ago, the Beijing government did not care that the co-pilot was a close friend of a young American naval officer called Donald Rumsfeld.

But now China cares so much that when it sent its most senior military officer to America for a visit this week, General Guo Boxiong handed over previously classified papers on the incident to Defense Secretary Rumsfeld.

An American official said the documents had yet to be translated, but appeared to contain the Chinese air force account of the shooting down of an American Mercator electronic surveillance aircraft in international airspace off Taiwan in August 1956. The pilot, 24-year-old Lieutenant James Deane, had trained with Mr. Rumsfeld in Florida.

China has acknowledged that its MiGs shot down the plane, but has denied claims it saved and then secretly held survivors. The papers are thought to confirm the official Chinese account.

Only four bodies were ever found from the 16-man crew. Deane’s was not among them and there have been questions about what really happened that night.

Suspicions deepened in 1992 when a previously classified American intelligence report was discovered saying two Americans, one of them matching the lieutenant’s description, had been moved to the house of a Chinese government official from a hospital. The document’s discovery fueled a private campaign by Deane’s widow, Dr. Beverly Deane Shaver, to discover what had happened to her husband of three months. She went to China and was told the incident was “classified.”

Mr. Rumsfeld first raised the issue with China when chief of staff to President Ford, 32 years ago. In response, Deng Xiaoping told Mr. Ford there was “no information” on what had happened to Deane. Over the years, China repeatedly denied the men had been taken alive. Eventually, Mrs. Shaver and Mr. Rumsfeld went public. “I remember the sorrow of losing him,” Mr. Rumsfeld said at the time.