ALBUQUERQUE, N.M. ' Los Alamos scientist Wen Ho Lee, who was fired and jailed on charges of mishandling nuclear weapons secrets, has agreed to plead guilty to one charge and will cooperate with federal investigators, Justice Department sources said Sunday. \nLee is expected to be released after a hearing Monday and be sentenced to time already served, ending a 3-year-old case that has been marked by allegations of espionage and racial profiling. \nThe accusations began as an offshoot of a Chinese espionage case with dire accusations that Lee had downloaded the "crown jewels" of American science, might be poised to hand them over to a foreign power and might even be spirited away by spies in helicopters. The government ultimately backed down from nearly all those charges. \n"Dr. Lee and his family are thrilled at the prospect that he may be released unconditionally tomorrow," defense attorney Mark Holscher said Sunday, adding that he cannot elaborate on terms of the settlement because they have not yet been filed. \n"Dr. Lee very much wants to go home to his family," he said. \nThe government sources, speaking on condition of anonymity, said a key turning point in the two months of plea discussions was Lee's agreement to explain what happened to seven computer tapes, onto which he was accused of downloading sensitive information. Lee has said the tapes were destroyed, now he will better explain how, the officials said. \n"The location and fate of the tapes were always of paramount concern," one of the officials said. \nThe sources said Lee will plead guilty to one of the 59 counts against him of unlawful gathering of national defense information. \nLee also will agree to hold himself completely available for federal investigators and cooperate with them over the next six months, the sources said, and it was expected that Lee would drop his allegations that prosecutors went after him because he is Chinese-American. \nU.S. District Judge James Parker announced that a plea agreement had been reached in a brief order Sunday. A Monday appeals court hearing in Denver on Lee's bail, which Parker had approved, was canceled. \nLee, 60, was accused of downloading restricted material about nuclear weapons to unsecured computers and tapes while working at Los Alamos National Laboratory. His trial had been set for Nov. 6, and he could have faced life in prison if convicted on all 59 counts. \nLee has been jailed since his arrest Dec. 10.