A Fairfax County prosecutor was found guilty of misconduct by the Virginia State Bar Wednesday for not correcting the false testimony of two key witnesses in a 2009 robbery and abduction trial.

The three-judge panel admonished Assistant Commonwealth Attorney Mark Sullivan, but did not suspend his license to practice law, a penalty sought by the State Bar.

The panel found Sullivan should have made clear that two of the case’s co-defendants, who testified against the alleged mastermind of the scheme, had cut deals with prosecutors in exchange for taking the witness stand. Both witnesses denied they had such deals during their testimony.

Richey Price and Antonio Wilson provided crucial evidence that led to the conviction of Devin Manigo and his sentencing to 15 years in prison for robbery and abduction.

During the trial, Price and Wilson testified Manigo recruited them and provided the taser the pair used to shock a clerk three times during the 2007 robbery of a Chantilly Prime Mart that netted about $30,000.

Manigo later challenged the conviction and pursued the State Bar complaint, saying Sullivan had failed to disclose crucial information that impugned Price and Wilson’s motives for testifying.

During an evidentiary hearing that followed, Sullivan testified that he agreed to reduce one of Wilson’s charges in exchange for his testimony against Manigo. Sullivan also testified that he would tell the sentencing court that Price and Wilson had cooperated with prosecutors.

Based on that evidence, Fairfax County Circuit Court Judge David S. Schell set aside the verdict in Manigo’s case in 2010 and ordered a new trial. Manigo later pleaded guilty to a lesser charge of conspiracy to commit robbery in the case.

Richard Slaney, assistant counsel for the State Bar, argued Wednesday that Sullivan had failed to perform a basic duty as a prosecutor.

“Mr. Sullivan had to know their testimony was false and had a duty to correct it,” Slaney said.

Sullivan testified that he thought Price and Wilson had testified truthfully on the stand, since he said neither had deals to testify in Manigo’s case. The testimony seemed to contradict some of his earlier statements that they had such deals.

“I didn’t tell either they would benefit from testimony,” Sullivan said.

Sullivan, who has been a prosecutor since 2004, also said Manigo’s case was one of the first he had handled where co-defendants were testifying against someone charged. He said he would likely handle it differently if he had another chance.

Manigo said Wednesday he was not fully satisfied with the ruling.

“[Sullivan’s] job is supposedly to seek justice and he violated the known rules of conduct,” Manigo said. “I don’t understand how they can just give him a slap on the wrist.”

It was the first time Sullivan has been disciplined by the State Bar, but not the first time questions have been raised about one of his cases.

Last November, a Fairfax County judge dismissed felony child cruelty charges against a former Fairfax County special education teacher, after Sullivan failed to disclose evidence to the defense until the night before the trial.