The D.C. Court of Appeals overturned the 1977 murder conviction of a Washington man yesterday, ruling he had been denied a fair trial because the judge permitted testimony about his prior criminal activity.

The three-judge appellate panel ordered a new trial for the defendant, William C. Rindgo, who was convicted of the murder, rape and robbery of a 24-year-old woman in Northwest Washington in 1974.

The panel ruled that Rindgo was denied a fair trial because Superior Court Judge Eugene N. Hamilton permitted the chief government witness, Edward Burke, to testify at length about a series of robberies he said he and Rindgo carried out before and after the slaying of Barbara Myersburg on Jan. 7, 1974.

During the trial, Hamilton overruled strenuous objections to Burke's testimony by Rindgo's attorney, Charles J. Murray, and permitted Assistant U.S. Attorney Girard F. Treanor to explore Rindgo's past criminal activities as "relevant background."

"We have long observed the rule that unless and until a defendant takes the stand or otherwise places his character in issue," the appeals court said, "evidence of a defendant's prior illegal activity is generally inadmissible because of its prejudicial impact."

"The prejudice to appellant here from the inference that could flow from evidence of his joint participation with Burke in prior robberies far outweighs any enhancement of Burke's credibility, . . ." the judges wrote.

"We must conclude that this evidence was so prejudicial that its admission denied appellant a fair trial and compels reversal."

Rindgo, 41, was convicted on March 3, 1977, after a weeklong trial in which Burke testified he saw Rindgo attack a woman in a parking lot near television station WTOP (now WDVM) at 40th and Brandywine streets NW on the night Myersburg was killed.

Police found the body of Myersburg, a ticket clerk for Pan American World Airways, near the television station the next day. She had been beaten, raped and strangled, according to evidence at the trial.

Rindgo testified that on the night Myersburg was killed, he was confined to a D.C. Department of Corrections halfway house in Southeast Washington, where he was serving a sentence for attempted rape and attempted armed robbery.

Burke was also arrested and charged with Myersburg's murder, but was given immunity in return for his testimony by the government. He told the jury he and Rindgo met at a Northwest bar that night, and planned the robbery of a gasoline service station to get money to buy drugs.

Burke, who said he had left his own halfway house without permission that night, testified that both men, armed with guns, drove to Wisconsin Avenue and Warren Street NW where they found the station they had planned to rob was closed.

At a second station, Burke testified, Rindgo got out of the car to inspect the station.A short time later, Burke said, he also got out of the car and heard a woman scream. He testified he saw Rindgo with his arm around a woman's neck. The woman struggled, then went limp, Burke testified.

Hamilton sentenced Rindgo in 1977 to serve from 31 years and 8 months to life in prison for his convictions of felony murder, rape and prison breach. t