A Philadelphia judge's fixation on a decades-old feud with the late actor Charlton Heston prompted a federal appeals court on Tuesday to overturn her conviction of a man charged in a 1997 murder.

Outlining an improbable series of events, the U.S. Court of Appeals for the Third Circuit found that Common Pleas Court Judge Lisa Richette overstepped the bounds of judicial propriety by calling the victim's family into her chambers midtrial to assure them that Heston had unfairly labeled her as "Let 'em Loose Lisa," suggesting she was soft on crime.

The movie icon, known for starring in Ben-Hur, The Ten Commandments, and Planet of the Apes, had singled out Richette a month earlier in a speech at the National Rifle Association's convention in Philadelphia.

"It's difficult to convey in excerpts the inappropriate nature of [Richette's] lengthy conference" with the family of Mark Gibson, who was killed during an argument with his roommate, Paul McKernan, in 1997, wrote Circuit Judge Jane Richard Roth in an opinion, joined by her colleagues D. Michael Fisher and Joseph A. Greenaway Jr.

Roth added: "It is even more difficult to understand why defense counsel failed to object to the proceedings or move for the judge's recusal at any point during the conference."

McKernan, who is imprisoned at a state facility in Somerset County, had been accused in 1998 of bludgeoning Gibson to death with an aluminum baseball bat, but he maintained that he struck his roommate only in self-defense.

He chose to forgo a jury trial, leaving the decision of his guilt or innocence solely in the hands of Richette, who died of lung cancer in 2007.

But Gibson's family was critical of her handling of the case from the start, citing Heston's jab at the judge on a website they created to track the proceedings.

"Lisa Richette is a bleeding-heart judge that often sympathizes with murderers and other violent criminals and gives them light sentences," they wrote in a comment that prompted Richette's midtrial decision to convene her conference with the family in her chambers.

According to court transcripts, the judge accused the Gibsons of writing "dreadful, slanderous things" about her and spreading a "total lie." But at the same time, she eagerly sought their approval, telling them she "just want[ed] to make sure that you folks are happy with me" and assuring Gibson's mother that "we're all mothers here."

She characterized the case as a "horrible, horrible murder" and told the prosecutor trying it that the Gibsons "had already been hurt enough, and I don't want them to have this case heard by a judge in whom they have no faith."

The family ultimately backed off on the criticism, even offering to let Richette write a defense of her record that they would post on their blog. But as they left to return to the courtroom, the judge cautioned them: "I don't want to open the Daily News tomorrow and read about the usual B.S."

In her opinion Tuesday, Roth wrote that "Judge Richette's actions would have caused any competent attorney to seek recusal immediately."

But McKernan's lawyer, W. Fred Harrison Jr., stood mute as he watched the unusual conversation play out before him, according to the transcripts.

After the Gibsons left Richette's chambers, prosecutor Mark Gilson raised concerns that the judge might have left the impression that she would bend over backward to please the family, and Harrison eventually joined in. But he set aside any lingering concerns after Richette called McKernan into her chambers separately and vowed to "try and pray to God that I be fair to you."

Eventually, she found him guilty of first-degree murder and sentenced him to mandatory life in prison without the possibility of parole.

In overturning McKernan's conviction, the Third Circuit concluded that he had received ineffective assistance from Harrison, who did not return calls for comment Wednesday.

"We're very happy that the court vindicated our arguments," said McKernan's appellate lawyer, Maria Pulzetti of the Federal Community Defender  Office. "Our client is relieved that that the court after nearly 20 years recognizes that he did not receive a fair trial."

The judges gave the District Attorney's Office two months to decide whether to retry McKernan or appeal Tuesday's ruling. A spokesman for the office said Wednesday that the matter remained under review.