Prosecutors at the murder trial of Richard Lee Earman contended yesterday that during his innocence, he privately told a cellmate that he killed an Arlington couple.

Arlington Commonwealth's Attorney William S. Burroughs maintained at the opening of Earman's jury trial in Arlington Circuit that Earman confessed to the cellmate that he had shot Alan W. Foreman and then had killed Foreman's fiancee, Donna Shoemaker, because she was a witness.

The existence of such a witness had been a carefully guarded secret and surprised Earman's defense attorneys. "It is absurd that he (Earman) would say something like that to someone he barely knows," one of those attorneys, John Zwerling, said in his opening remarks to the jury.

Earman is charged with two counts of murder and two counts of using a firearm in the commission of a felony, all in connection with the slayings of Foreman and Shoemaker last May 8. He faces a maximum penalty of life imprisonment.

Foreman, 26, a real estate agent, and Shoemaker, 25, were found shot to death in Foreman's blood-spattered yellow Jaguar in the garage of his home at 1201 N. George Mason Dr., Arlington.

Burroughs, in his opening argument before Judge Charles H. Duff, identified his surprise witness only as "Mr. James." It later was learned that he is Ronnie James, who was incarcerated in the Arlington County jail for violation of parole.

Earman has been held without bail in the Arlington jail since his indictment last June on the murder charges. Burroughs did not specify yesterday when the confession reportedly took place. James has since been temporarily transferred out of the county for his protection according to a source close to his case.

Burroughs contended in his opening argument that Earlman killed the couple as part of a scheme to collect the dead man's $56,000 life insurance policy.The insurance agent who sold Foreman the policy, Joseph N. Martin, also has been charged with the murders, and is scheduled to stand trial Oct. 31.

The beneficiary of that policy, Charles Silcox, a district manager for Door Stores, also had been charged with the murders, but Burroughs dropped charges against him last week for lack of evidence.

Zwerling argued yesterday that Earman cannot account for what Martin might have done, and has no idea how or why the couple was killed.

"Foreman was deeply in debt and borrowed $4,000 from Martin and associates. He wasn't shot for $4,000," Zwerling said. He suggested that whomever he might have owed a lot of money, possibly gamblers, loan sharks or drug dealers, might be responsible.

Burroughs contended that Earman left Tramps, a Washington discotheque, with Foreman and Shoemaker, and then shot them from the back seat of their car in the predawn hours of Saturday, May 7. The bodies were found the following d following day when a neighbor became suspicious and looked in a garage window.

After shooting the pair, Burroughs continued in his opening argument, Earman tried to cover up his involvement. He has given several versions of his actions that night to police, to neighbors, and to cellmates, Burrough said.

Zwerling said that police found blood "from one end of that (Foreman's) house to the other," as well as muddy footprints, but that examinations of Earman's clothing and car have failed to link any such mud or blood to Earman.

Burroughs noted that police, observing from a distance, had seen Earman clean out a car shortly after police had questioned him about the killings. Zwerling maintained that his client did this only because "he was a nut about keeping his car clean," and pointed out that he was doing it three days after the murders.

A neighbor of Foreman's will testify that she heard five shots the night of the murders, and got a glimpse of a car roaring away from the dead man's house, Zwerling said. At a subsequent police "lineup" of automobiles, driven away from the same point in the dark, the nieghbor identified a Chevrolet Chevelle as the getaway car, Zwerling said. His client drove his won Mercury Cougar from the house that night, he said.

Barman has maintained in an interview with The Post that he went drinking with Foreman and Shoemaker that night they were killed, rode back to their home in their car, then left in his own car when they wanted to continue on to get something to eat.

Both Foreman and Earman were real estate salesmen for Town and Country Properties, Inc., and had been working together on a business deal in the week before Foreman murdered. Zwerling told the court yesterday. That business deal, he added, had nothing to do with loans or insurance policies.

One of the prosecution's star witnesses, Ray Moore Tugwell Jr., testified yesterday as he had at his preliminary hearing last month, that Earman had asked Tugwell last February "if I would accept a contract to do a hit."

Earman offered tugwell $5,000 to kill another agent who worked with him at Town and Country, and promised to pay him from an insurance policy after the job was done, Tugwell testified yesterday.

Tugwell said he had told Earman that nothing could be done without money in advance, and subsequently he Tugwell became alarmed when he read accounts of the shootings in a newspaper. He went to the police with information because he was "bothered" by the killings and because he feared complicity, Tugwell testified.

Tugwell said that he had known Earman since childhood. Both men were convicted in the 1960s of being part of a Beltway Burglars gang that allegedly committed 5,000 break-ins in the Washington area.