Terrence G. Johnson, convicted in 1979 of voluntary manslaughter in the death of one Prince George's County police officer and found innocent in the death of another, was back in court yesterday asking a circuit judge to set aside his conviction and 25-year prison sentence.

Johnson's attorneys asked Judge G.R. Hovey Johnson to overturn their client's conviction because the trial judge didn't inform defense attorneys about a conversation he had with a juror who claimed that the jury foreman had told her that the black jurors "were sticking together." Johnson's attorneys found out about the conversation a year after the conviction, when a national law organization surveyed the jurors.

Johnson, who is black, was charged in June 1978 with the slayings of officers Albert M. Claggett IV and James Brian Swart. Both officers were white. Johnson, who was then 15 years old, and his brother had been picked up by police as suspects in a burglary. The two officers were shot inside the station.

Johnson's attorneys asked Circuit Court Judge Howard S. Chasanow to overturn the conviction because they had not been informed about the conversation.

Chasanow denied the request, saying that Johnson's and his attorneys' absence from the meeting where the judge learned of the conversation didn't adversely affect Johnson's case. The Maryland Court of Special Appeals upheld Chasanow's ruling.

But a federal court sent the case back to the state courts, saying that Chasanow's ruling did not address the issue.

Fisher said at yesterday's hearing that had Johnson's attorneys known about the conversation, they might have asked for a mistrial or to have the foreman removed from the jury.

Judge Johnson is expected to rule in the case within 30 days.