The sexual assaults occurred in April 1997 while Johnson was awaiting trial on kidnapping, attempted murder and other charges in Jefferson County.
Berkeley County Prosecuting Attorney Pamela Games-Neely asked Sanders to make the sentences consecutive.
Johnson has appealed the earlier conviction, arguing he should not have been found guilty of kidnapping the Gaithersburg, Md., man because he thought he was hauling the man's corpse in the trunk of the stolen car.
Games-Neely said that she was concerned that Johnson could be released if he successfully appeals the kidnapping conviction.
"It's one thing to be locked up in jail and it's another thing to be brutalized in jail," Games Neely said. "Not only do we have to protect the people on the outside, we have to protect the people on the inside."
Johnson's attorney, David Camilletti, argued that the sexual assault sentences should be concurrent with the life sentence since there was no chance for parole.
Camilletti also argued the victim was not believable on the witness stand and that the jury, which deliberated for 22 minutes before finding Johnson guilty, had made a mistake.
Johnson told Sanders that he believed the jury convicted him because he is black.
He said there was only one black on the jury. He also blamed publicity from his kidnapping trial.
"I feel ... jurors had made their minds up to find me guilty before they even sat on the panel," Johnson said. "I know well they read the papers and knew who I was."
Sanders denied Camilletti's motion to throw out the jury's verdict.
Johnson asked through Camilletti for the judge to have the state take him to a state prison rather than keeping him in the Eastern Regional Jail.