A Prince George's County Circuit Court jury acquitted a former prisoner in the county jail yesterday of sexually assaulting a fellow inmate.

The jury deliberated for one hour and 20 minutes before finding Dwight Welcher, 32, not guilty of sexually assaulting Ralph Bunche Gordon, 29, in October 1980 at the County Detention Center.

The prosecution of Welcher, who is serving a 20-year sentence for armed robbery, was the last of 14 prompted by a Washington Post series detailing sexual assaults among prisoners at the county jail. Eleven of the men were convicted.

Post reporter Loretta Tofani, who won a Pulitzer Prize for the series, quoted Welcher as saying that sexual assault was an assertion of his power over other inmates.

"In jail, manhood is everything because you have nothing else," Welcher told Tofani.

Gordon, who is serving a 35-year sentence for raping three women, testified at the trial that Welcher raped him and forced him to perform sodomy.

Gordon submitted, he testified, because "I feared for my life. He told me he would kill me." During the incident, he testified, "I just kept saying to him, 'Would you stop? It hurts.' "

But other prisoners testified that they had not seen Gordon assaulted or heard him complain about being raped.

Welcher did not take the stand during the two-day trial.