The prosecutor stood before the jury, brandished a legal pad and in a grave voice began to read from a letter she said showed Brian P. Regan was a spy.

"I am willing to commit espionage against the United States by providing your country with highly classified information," Assistant U.S. Attorney Patricia Haynes quoted Regan as writing in a letter to Libyan leader Moammar Gaddafi found by federal agents on a laptop in Regan's home.

Turning and pointing at Regan as she began her opening statement at his trial yesterday, Haynes said: "These are the words of this man, Brian P. Regan. He attempted to give our country's most sensitive information to Iraq, Libya and China. . . . Brian Regan took an oath of loyalty to the United States. It was an oath he did not keep."

But the government's depiction of Regan -- a father of four from Bowie who could, if convicted, become the first espionage defendant to face execution in the United States in half a century -- contrasted sharply with the image offered by defense attorneys. They portrayed Regan as a decorated government employee with an active fantasy life who was merely "playing spy." While acknowledging that Regan "mishandled" classified documents, they said he had no intention to, and never did, harm the country.

"This is not a case of espionage or attempted espionage," defense attorney Jonathan Shapiro said in his statement to the jury of nine men and seven women, including alternates. "This may be a case of bad judgment bordering on stupidity."

Regan, 40, a former Air Force intelligence analyst, was arrested at Dulles International Airport in August 2001 as he boarded a plane to Switzerland. He has pleaded not guilty to three counts of attempted espionage for allegedly trying to sell classified documents to Iraq, Libya and China and to one count of gathering national defense information.

The trial, expected to last about two weeks in U.S. District Court in Alexandria, is unusual in several ways. It is uncommon for espionage cases to be tried, in part because the government often seeks to strike a plea deal with defendants to obtain more information about the damage done. Officials also fear the release of sensitive data. U.S. District Judge Gerald Bruce Lee is guarding against that in Regan's case by allowing jurors to view classified documents on a large television screen not visible in the rest of the courtroom.

The government's decision to seek the death penalty for Regan has been controversial because far more renowned spies, such as the FBI's Robert P. Hanssen and the CIA's Harold J. Nicholson, did not face execution. Defense attorneys cited these other cases, and the fact that Regan is charged only with attempted espionage, in vehemently arguing that the death penalty is not appropriate. Those arguments were rejected by a federal judge.

Two of the four counts carry a death sentence.

Looking directly at the jurors, her hands clasped over a podium, Haynes portrayed Regan as a calculating and deceptive man struggling with $116,000 in credit card debt. Regan stared impassively at Haynes and took notes on a yellow legal pad.

Regan enlisted in the Air Force at 17 and began working in 1995 at the super-secret National Reconnaissance Office in Chantilly, where construction and operation of the nation's reconnaissance satellites is overseen. There, he administered the Intelink Web site accessible only by the intelligence community. After his retirement, he was hired by defense contractor TRW Inc. and resumed work at the reconnaissance office July 30, 2001, court documents say.

By that time, the FBI had started daily surveillance on Regan and had bugged his home telephone, according to testimony from FBI agent Steven Carr, yesterday's first prosecution witness. The agency soon began electronic monitoring of Regan's office computer.

Regan drew the attention of investigators after the United States learned that Libya had obtained classified U.S. documents and that Libyan officials had received encrypted messages telling them to contact a free e-mail account under the name "Steve Jacobs," court documents say. FBI agents determined that the Jacobs account had been accessed from public libraries in Crofton, Falls Church and Prince George's County. The two Maryland libraries are within five miles of Regan's home; the Falls Church library was on his commuting route.

After Regan was arrested, FBI agents searched a computer in Regan's home. Although it took nearly six months -- a delay Haynes attributed to the Sept. 11, 2001, terrorist attacks -- investigators eventually found the letter offering to sell government secrets to Libya and a similar letter written to Iraqi President Saddam Hussein that sought $13 million.

It remains unclear whether Regan ever sent those letters, and defense attorneys argued that they were an act of fantasy by a man who couldn't go through with any plans he may have made.

At best, Shapiro told jurors, the letters were "a ridiculous fantasy with absolutely no chance of success." He said the letters were "consistent with other fantasies" in Regan's life, including a novel he started about mind transplants and "odd inventions" he frequently spoke about.

Shapiro argued that the encrypted coordinates to missile sites in China and Iraq that Regan was carrying would be useless to any foreign government and were so simple that they were "ridiculous, almost child's play." When Regan obtained the coordinates, he removed all classified information, Shapiro said.

Conceding that Regan was in debt, Shapiro said that it was because of college tuition and that his debts had been fully disclosed to the government to obtain his security clearances. "Was this a ruthless man out to sell out his country or was this something entirely different?" he said to the jury.

Brian P. Regan watches an FBI videotape on the opening day of his federal trial. The defense called the former Air Force enlistee a decorated employee who was merely "playing spy."Brian P. Regan, foreground, listens as Assistant U.S. Attorney Patricia Haynes addresses Judge Gerald Bruce Lee and jurors during the first day of Regan's trial.