Richard Lee Earman, who has pleaded guilty to conspiring to murder a young Arlington couple, has admitted committing more than 200 burglaries of Fairfax County business establishments since 1977, according to county police.

Police said "tens-of-thousands-of-dollars" were taken in the break-ins and that Earman, 36, who served the years in prison after a 1968 burglary conviction, used the money to live on.

Earman's admissions have enabled police to close their investigations of "the majority of unsolved commercial burglaries" committed in the county between 1977 and this year, according to Fairfax County police detective Bob Keyes.

There are no plans to prosecute Earman for any of the burglaries, but he could be sentenced to as long as 10 years in prison for his guilty plea to murder conspiracy, which he entered last month as part of a plea bargain.

Keyes said Earman used forced entry methods like the ones used in a series of Fairfax burglaries in the 1960s when he was a member of the so-called Beltway Bandits gang. That gang was held responsible for more than 5,000 burglaries of Washington-area homes. Earman's 1968 burglary conviction came as a result of his involvement with that gang. nly money was stolen from cash registers or safes in the latest series of burglaries, according to Keyes and since Earman is believed to have used the money to live on, virtually none of it is likely to be recovered.

"Naturally, if we could close these cases and charge him [Earman] with them, that's what we would have done," said Keyes. "But we had insufficient evidence to charge anybody."

As part of Earman's plea bargain last month, he is expected to testify at the forthcoming trial of Joseph N. Martin, 28, who is charged with murder and conspiring with Earman to murder Alan Foreman and Foreman's fiance, Donna Shoemaker, in order to collect on a $56,000 life insurance policy. If convicted, Martin, who has pleaded innocent, could be sentenced to death.

Earman, who already has been acquitted by a jury of murder charges in the case, cannot be retired for murder. He has testified at a preliminary hearing for Martin that he and Martin planned the slayings and that he shot the couple to death in Foreman's north Arlington home in May 1977.

Earman's admissions about the Fairfax burglaries were disclosed yesterday during an arraignment and bond hearing for Martin in Arlington Circuit Court.

Martin's attorneys urged Judge Charles S. Russell to delay their client's trial until September to give them time to prepare "the complicated case."

One of the attorneys, Gerald Treanor, told the judge that "200 burglary charges were dropped" against Earman in Fairfax as part of Earman's plea agreement and that this "may show bias" on Earman's part and provide incentive for him to testify against Martin.

Arlington Commonwealth's Attorney William S. Burroughs said later that Earman had been charged with only one burglary, and that Fairfax authorities agreed to drop that charge. He said Earman's cooperation in closing the unsolved burglary cases was not part of the official plea agreement.

In urging Judge Russell to raise Martin's bond from $2,500 to $100,000, Assistant Commonwealth's Attorney Helen Fahey said, "This is probably one of the most brutal and cold-blooded murders in the history of Arlington County."

In reply, Louis Koutoulakos, one of Martin's attorneys, attacked Earman's credibility and noted that his client showed up for yesterday's court appearance although the bond was only $2,500.

The judge scheduled Martin's trial for July 9 and increased his bond to $50,000. Martin was free under bond last night. CAPTION: Picture, RICHARD LEE EARMAN . . . only money was stolen