Washington ? A manuscript given to the Library of Congress may solve a mystery as old as the American Revolution: how the British caught and executed Nathan Hale for spying.

It turns out that Hale, considered by the CIA to be the first American executed for spying for his country, probably made some monumentally naive mistakes — chief among them trusting a stranger with the secret of his mission. Those blunders could have led to his hanging 227 years ago this Monday.

Details of Hale’s capture have eluded historians, but library officials have new information from the manuscript, written during or soon after the Revolution by Consider Tiffany, a Connecticut storekeeper and British sympathizer. The document was donated to the library in 2000 by a descendant, G. Bradford Tiffany.

According to James Hutson, head of the library’s manuscript division, the document appears to identify Maj. Robert Rogers, a British hero from the earlier French and Indian War, as the man who trapped Hale by pretending to be a Colonial spy himself.

A handsome, athletic Connecticut schoolteacher and Yale graduate, Hale was an enthusiastic patriot who rose quickly in the Continental Army and was promoted to captain in 1776. Later that year, Gen. George Washington, the army’s commander, was driven out of Long Island by the British and badly needed information on the enemy’s strength and plans, which meant sending a spy into British territory.

Hale volunteered — by some accounts he was the only volunteer — saying it was his patriotic duty.

“I wish to be useful, and every kind of service necessary to the public good becomes honorable by being necessary,” he told Capt. William Hull, a friend from his regiment who tried to dissuade him.

Hale put on civilian clothes and left his uniform, silver shoe buckles and papers with a fellow soldier. He found a boat to cross from Norwalk, Conn., to Long Island, where he slipped behind enemy lines.

A statue of Nathan Hale stands outside CIA headquarters in Langley, Va. A manuscript given to the Library of Congress may solve a mystery as old as the American Revolution: how the British caught and executed Hale for spying.

Untrained in the arts of spying, Hale evidently was easy prey for the canny Rogers, an expert frontier warrior who had led a group of highly trained rangers in the French and Indian War.

Rogers recently had escaped from American captivity and was recruiting troops for the British on Long Island. According to the Tiffany manuscript, Rogers had been observing Hale for some days, suspecting that the young man was in disguise. He decided to engage him in conversations about the war.

Rogers led Hale to believe they were on the same side and that he himself was “upon the business of spying out the inclination of the people and motion of the British troops,” Tiffany wrote.

The unsuspecting Hale told Rogers of his own mission, and Rogers invited him to dinner at his quarters, where he and several friends began the same kind of talk, the manuscript said.

“But at the height of their conversation, a company of soldiers surrounded the house, and by orders from the commander, seized Captain Hale in an instant,” Tiffany wrote.

The rest of Hale’s story was reported by his friend Hull, who got his account from a British officer sent to Washington’s headquarters for an exchange of prisoners. The officer, Capt. John Montressor, told him that Hale had taken notes on British forces and was brought before the British commander, Sir William Howe, in Manhattan.

“Those papers, concealed about his person, betrayed his intentions,” Hull reported. “He at once declared his name, his rank in the American army, and his object in coming within the British lines.”

The British hanged Hale the next morning, Sept. 22, 1776, at an artillery park near Dove Tavern. Historians place it near what is now 66th Street and Third Avenue in Manhattan.

It was there Hale is reputed to have uttered his famous line: “I only regret that I have but one life to lose for my country” — likely a paraphrase of a line from a popular play by British writer Joseph Addison.