A U.S. District Court jury in Alexandria acquitted two Lorton prison inmates yesterday in the fatal stabbing of another inmate last July.

Antonio Smith, a 22-year-old Southeast Washington man imprisoned for petty larceny, died July 2 of a stab wound to his neck inflicted with a single blade from a pair of scissors.

The jury deliberated two hours before acquitting Sibley Hammond, 19, a convicted armed robber, and Calvin Dudley, 22, convicted of possessing marijuana with intent to distribute it, in the slaying, which occurred at the District of Columbia's Lorton Youth Center II in southern Fairfax County.

Seven inmates took the witness stand, several testifying they saw Hammond take an "object wrapped in newspaper" from a hole in the ceiling the night before the slaying and that Hammond was standing next to Smith when the stabbing occurred and Dudley was nearby.

In his closing arguments, defense attorney Gary Kohlman asked jurors to consider the source of the case against the defendants. "They are heroin addicts, thieves and liars," he said, referring to the prosecution witnesses.

Hammond and Dudley were the FBI's prime suspects and prosecuters said they doubted if another investigation into the killing would begin.

Defense attorney Bradley Evans argued that Lorton was "known as a violent place," and that "there were dozens of people there with access to weapons who would strike another with little provocation." He reminded the jury that no fingerprints were found on the weapon, nor was it determined how the scissors entered the prison.

Hammond and Dudley, neighborhood friends from Southwest Washington, sat showing no emotion during the two-day trial. When the verdict was announced, they turned their heads and looked back for the first time at the two rows of friends and family behind them.