Despite pleas yesterday by Prince George's County Executive Lawrence J. Hogan and Police Chief John Rhoads asking county police officers to stay on the job, police union officals predicted that most officers would stay home today to protest the verdict in the Terrence Johnson case.

Widespread anger that a jury found the 16-year-old innocent of first-degree murder in the slayings of two police officers makes the walkout virtually inevitable, police union president Laney Hester said yesterday.

Johnson had been charged with two counts of first-degree murder after the June 26 shooting deaths of officers Albert M. Claggett IV andJames Brian Swart. After a two-week trial, jurors Saturday found him guilty of one count of manslaughter and a weapons offense.

The decision in the emotional case left neither side happy. At a noon press conference yesterday, defense attorney R. Kenneth Mundy said that he would appeal the two convictions Johnson, he said, has a "50-50" chance of eventually going free.

At his won hastily called news conference at police headquarters yesterday. Chief Rhoads sharply criticized the verdict, in an apparent attempt to win support for his efforts to keep police officers on the job. Earlier in the day, Rhoads had contacted Maryland State Police and alerted them to the possibility of a walkout.

At the news conference, Rhoads said that, "Certain persons have used this [Johnson] trial is an indictment of the Prince George's County police department. I am quite shocked by the verdict and extremely concerned about the effects of it on this department and on the community."

"Right now, my men are asking me why. Why two police officers could be shot down and the jury doesn't come back with a guilty verdict. I think two of my men were murdered. The rest oof us are extremely upset and frustrated by what happened."

Rhoads said he "guaranteed" that his men would be at work this morning. Later, however, after learning from Hester that the union expected few officers to report to work, Rhoads said he hoped that a tape recording of the press conference to be played at last night's 10 p.m. roll calls would change things."

A police spokesman said last night that the number of officers reporting for that shift appeared to be "normal for a Sunday," and that no station was shortstaffed. He declined to be more specific.

Other department sources said, however, that absenteeism at the two largest stations, Hyattsville and Seat Pleasant, was about 25 percent-15 to 20 percent above normal.

Many policemen gathered at the union's headquarters outside Upper Marlboro on Saturday night to discuss their frustrations. The jury of eight whites and four blacks found Johnson innocent by reason of insanity on six charges connected with the death of Swart and guilty of the two lesser charges in connection with the death of Claggett in the Hyattsville police station.

The slaying of two white officers by a black youth whom they had in custody became an event that crystallized some of the longstanding hostility between the largely white, 837-member police force and the increasing number of black county resiidents.

Many supporters of Johnson contended, as did his defense attorney, that the youth was being beaten by the police officers and acted in self-defense. Prosecutors and other policemen, however, saw Johnson as a cold, arrogant young killer.

As part of their effort to keep the angry officers on the job, Hogan and Rhoads made a second tape recording last night at police headquaters urging the men to report for work in the morning. In an article on the oped page of today's Washington Post, Hogan made a similar appeal.

"We're trying to appeal to them to remember their oath of office to come to work always, not just when it's convenient," Hogan said. "The people they'll hurt by this are the citizens of the county and they're innocent."

Hogan said last night he would contact Governor Harry R. Hughes to make him aware of the situation. In the meantime, state and county police officials met last night to map out plans for the morning.

"We will have our men in the College Park and Forestville barracks on 12-hour shifts and we'll have extra troopers on duty there," said State Police spokesman Bill Clark. "We'll also have men on call to come down from other parts of the state if necessary."

The union represents all memerbs of the police force through the rank of lientenant, about 810 of the 837 men on the force.

Hester said yesterday the union has not sanctioned a strike but said that given the anger most of the men felt over the verdict, Rhoads and Hogan's appeal "was a dollar short and a day late."

"The verdict was b . . .," and everyone is extremely angry about it," Hester said. "That jury said that the lives of two policemen don't mean a f . . .. I think most guys thinks they owe this to Rusty and Brian."

After the verdict was returned Saturday, Hester said that "Anyone threatening a Prince George's County police officer or pulling a gun on them better be ready to meet his marker."

Yesterday Rhoads said, "That was a terrible statement. But I think it was said in anger, out of frustration. I don't think he meant it."

Hester said he stood by the comment. "John Rhoads has enough problems talking for himself without taking on the extra burden of talking for me," he said.

Yesterday morning at the Brentwood Baptist Church where the Johnson family has attended services since shhootings, the Rev. Perry A. Smith told the congregation that Johnson had asked him to say taht "he loves you all."

"I hope this community can pull itself together now that this trial is over and put the pieces together," Smith said later. "Many members of my congregation were very upset that Terrence wasn't fully acquitted.

"But I hope the police will face the realities of the times, comppose themselves and continue to do their jobs."