A former Navy physicist arrested in an Internet pornography sting was sentenced to six years in prison today during an emotional proceeding that was attended by most of the jurors who found him guilty.

George P. Chambers, 46, a married father of two young daughters, was convicted in U.S. District Court here in March of seducing a 13-year-old girl -- in reality, an FBI agent -- over the Internet and of possession of child pornography.

All but two of the jurors, some of whom had come from as far as the Eastern Shore, were in court Wednesday, an event that defense attorney Bryan A. Levitt called unprecedented in his 18-year career. In the hallway outside, jurors spoke of their desire for "closure" and of the ties that had developed among them. "And we have children," said one, Marta Miller of Baltimore.

What they heard Wednesday was Levitt promising to appeal, telling U.S. District Judge Marvin J. Garbis that FBI agents who testified for the prosecution committed "outrageous perjury," a conclusion Garbis disputed.

Levitt described Chambers as a brilliant physicist, citing "extraordinary contributions" in developing weapons to attack caves in Afghanistan and advances in cancer treatment. "The sooner he can get back to work, the better off we in the United States are going to be in terms of our security," Levitt said. After he was indicted, Chambers, of La Plata, lost his job as a weapons designer at the Naval Surface Warfare Center in Indian Head.

Assistant U.S. Attorney Ari S. Casper countered that Chambers perjured himself when he testified and had, at one point, yelled at a witness.

Under sentencing guidelines, Garbis could have imposed a sentence between 70 and 87 months. He chose 72 months, citing the two years Chambers has spent under home confinement.

But before Garbis did so, Jimmy Chambers, 89, stood to address the court. He said his nephew's offenses were "insignificant" compared with his contributions. He turned to the jurors in the courtroom. "He has saved the lives of many of your children," he said, wagging a finger. "Shame on you. Shame. Shame. Shame."

George Chambers was arrested by agents working for Operation Innocent Images, an initiative started in the FBI's Baltimore field office in 1995. The initiative, which has been embraced nationally, has resulted in 3,316 convictions, the vast majority gained through guilty pleas, according to the FBI.

Chambers used an unusual defense that, according to Levitt, has been successful in only two other cases. His defense claimed that Chambers was engaged merely in "net fantasy" and that he never intended to follow through on his proposals to the undercover agent. Chambers was first tried in 2002, but that trial ended when the jury announced that it was deadlocked.

During the second trial, prosecutors added the child pornography count and introduced photo images they said had come from Chambers's auxiliary drive, an assertion Levitt denied Wednesday. Chambers, who recently found work as a graphics designer earning $7.50 an hour, declined to address the judge. Outside court, he said: "Obviously six years in prison, I think, is ridiculous."

Garbis ordered that Chambers begin serving the term July 23. The judge said he would recommend a low-security prison.