The D.C. court of Appeals yesterday overturned the 1977 conviction of a local businessman, Herbert Springer, for conspiracy to murder his estranged wife because the court said, the trial judge had improperly restricted defense attorney's questions of a key government witness.

On the same grounds, the three-judge appellate panel also reversed the convictions of Springer's co-defendant, Reginald Turner, on charges of conspiracy and solicitation to commit murder.

Springer had told several friends, including Turner, that he would pay $30,000 to get his wife, Sally, "off his back," according to trial testimony.

Turner, a Washington real estate man, told a paroled convict, Clarence W. McFarland about the plot.McFarland reported the story to the FBI, which contacted the D.C. Police, according to the testimony.

As a result, an undercover police officer posed as a "hit man," staged the death of Sally Springer, and arrested Springer after accepting $100 - part of a $10,000 fee for the job.

Springer, formerly of Chevy Chase, operated two stores in Washington that sold judicial gowns and choir robes, according to neighbors and Springer's attorney at the time of Springer's arrest.

After 37 minutes of deliberation, a jury convicted both men of conspiracy and solicitation to commit murder. Springer, then 47-year-old, was sentenced to serve a minimum of 18 months in prison and Turner, then 36, was sentenced to one year in jail. Turner since has been released on parole and Springer is in a Department of Corrections halfway house.

On appeal, both men argued that Judge Nicholas S. Nunzio had unfairly restricted their attorneys from cross-examining McFarland about his role as a paid government informant and possible financial motive behind his cooperation with law enforcement authorities.

The appeals court agreed that Nunzio had denied the men their constitutional right to effectively question McFarland in an effort to damage his credibility as a witness.

"The trial court's error in curtailing cross-examination of McFarland is rendered more egregious by the fact that McFarland was a key government witness," Chief Judge Theodore R. Newman Jr. said in an opinion for the court. Associate Judges John W. Kern III and J. Walter Yeagley also participated in the decision.

The appeals court let stand Springer's conviction for solicitation to commit murder, which was based on conversations with the undercover police officer and not McFarland.

In a related decision, the same appellate panel reversed an assault conviction of a former D.C jail guard, again because the trial judge had erred in restricting the cross-examination of a witness by a defense attorney.

The trial judge in that case was Chief Judge Harold H. Greene.The defendant, Issac M. Webb Jr., was accused of assaulting a visitor at the jail with a blackjack.