When a shadowy American who became a sworn member of al-Qaida was captured in Pakistan in 2008, U.S. intelligence officials sensed they had struck gold.
The young jihadist was whisked away to a New York courtroom in early 2009, where he secretly pleaded guilty to terrorism charges and was then held in seclusion. His identity _ but not much else _ was made public a few months later.
More than three years later, the world could get a full introduction to Bryant Neal Vinas at a trial starting Monday of another man accused in a foiled plot to attack New York City subways.
Vinas' name appears on a list of potential witnesses in the case against Adis Medunjanin _ and officials say he would offer a unique perspective on the inner-workings of the terror group and how it indoctrinates born-in-the-USA extremists.
Medunjanin has pleaded not guilty in federal court in Brooklyn to charges accusing him of traveling to Pakistan with two former high school classmates from Queens, Najibullah Zazi and Zarein Ahmedzay, to seek terror training there and hatch their scheme back home.
Zazi, a former Denver airport shuttle driver, and Ahmedzay have admitted in guilty pleas that they wanted to avenge U.S. aggression in the Arab world by becoming martyrs in a suicide attack on Manhattan subway lines in 2009. Both men are key government witnesses against Medunjanin.
Vinas, 29, was never charged in the case. But he's an intriguing and valuable cooperator because he had extraordinary access to al-Qaida's leadership, a U.S. official said.
Known by the nicknames "Ibrahim" or "Bashir al-Ameriki," Vinas met on a few occasions with Abu Yahya al-Libi, al-Qaida's now No.2. He also mixed with Mustafa Abu al-Yazid, the top commander in Afghanistan and Atiyah Abd al-Rahman, who orchestrated a plot involving a double agent that led to the killing of seven CIA employees _ both since killed in drone strikes.
A video released in October 2008 and shot at an al-Qaida outpost shows al-Libi with an armed man believed to be Vinas _ his head wrapped in a scarf and an ammo belt around his waist _ a month before his capture, said the official, speaking on condition of anonymity because the case is ongoing.
Vinas also could captivate the jury with his personal tale of radicalization _ a subject of intense interest to counterterrorism officials concerned about homegrown threats. He also could explain what convinced him to betray al-Qaida.
"He's a fascinating story," Steve Zissou, Vinas' lawyer, said while declining to confirm if his client will indeed testify.
The story began in Medford, N.Y., a suburban community on Long Island where Vinas grew up as the son of a Peruvian immigrant. His childhood seemed unremarkable: Family and friends have said he went to a Catholic church, blended in at the local high school and had a passion for baseball.
At some point, Vinas took the name Ibrahim and began attending services at the Islamic Association of Long Island, a mainstream mosque in nearby Selden. The president of the mosque recalled him as "very quiet, polite, smiley" _ a calm disposition that apparently masked a growing resentment toward his own country.
By his own admission, Vinas traveled to the dangerous tribal lands of northwest Pakistan, intent on fighting against U.S. forces in Afghanistan. Unlike other aspiring terrorists who didn't survive the al-Qaida vetting process, Vinas apparently was embraced.
Vinas told a judge he swore loyalty to the terrorist organization and underwent weapons and explosives training. In September 2008, he took part in a failed attack using rockets on an American base in Afghanistan.
Bashir al-Ameriki had at least two other assets that made him valuable as a fledgling al-Qaida operative: A U.S. passport that could let him slip back into the United States undetected and a firsthand knowledge of mass transit.
He admitted in his plea that he had "consulted with a senior al-Qaeda leader and provided detailed information about the operation of the Long Island Rail Road system which I knew because I had ridden the railroad on many occasions."
The purpose, he added, "was to help plan a bomb attack" of a rail line packed with commuters each day.
U.S. intelligence intercepted communications among extremists chatting about an "Ameriki," but initially puzzled over his identity.
A former U.S. counterterrorism official with direct knowledge of the case said the CIA "connected the dots" that ultimately led to Vinas' arrest by the Pakistanis in November 2008 in the bustling city of Peshawar, a hub of violent extremist activity.
Within days of his arrival in New York, a frightened Vinas started telling a team of FBI agents and New York Police Department detectives with the Joint Terrorism Task Force everything he knew, said the former official, who wasn't authorized to discuss the case and spoke on condition of anonymity.
Vinas demonstrated a keen grasp of names and places, officials said. He's credited with disclosing the identities of suspected terrorists, the locations of al-Qaida safe houses and discussions about potential civilian targets in the United States and Europe _ information that was shared throughout the intelligence community.
By pleading guilty to conspiracy to murder U.S. nationals, Vinas faces a maximum term of life in prison, though his cooperation could win leniency.
No sentencing date has been set.
Associated Press writers Eileen Sullivan contributed to this report.