A Philadelphia Common Pleas Court judge ruled Thursday that convicted cop killer Mumia Abu-Jamal can re-argue an appeal before the Pennsylvania Supreme Court because then-Chief Justice Ronald D. Castille did not recuse himself due to his prior role as Philadelphia district attorney when Abu-Jamal was appealing his case.

Judge Leon Tucker, however, denied for lack of evidence Abu-Jamal’s claim that Castille had “personal significant involvement” in Abu-Jamal’s case while Castille was in the District Attorney’s Office.

Dustin Slaughter, spokesperson for District Attorney Larry Krasner, said in a statement that “we are aware of Judge Tucker’s opinion and are currently reviewing it. As such, we have no further comment at this time.”

Judith L. Ritter, an attorney for Abu-Jamal, said in a statement that “Judge Tucker recognized the unconstitutional bias involved with Justice Castille’s sitting on the prior post-conviction appeals, and the need for a new appeal untainted by such bias. This was a straightforward application of federal and Pennsylvania law requiring cases to be decided by judges whose impartiality cannot reasonably be questioned.”

Abu-Jamal, 64, a former Black Panther and sometime radio reporter, is serving a life sentence for the Dec. 9, 1981, shooting death of Philadelphia Police Officer Daniel Faulkner, 25, at 13th and Locust Streets.

Castille served as district attorney from 1986 to 1991, then joined the Pennsylvania Supreme Court in 1994 and became chief justice in 2008 before retiring in 2014.

In October, Maureen Faulkner, the slain officer’s widow, was ejected from Tucker’s courtroom after she disrupted a hearing with an emotional outburst decrying the judge’s granting Abu-Jamal’s lawyers an extension in a two-year-old appeal.

Abu-Jamal’s lawyers filed this appeal on Aug. 7, 2016, following a U.S. Supreme Court decision that year that found Castille was wrong to have participated in an appeal to the state Supreme Court by another convicted killer.

Tucker wrote in his 36-page opinion that under the Williams v. Pennsylvania decision, “if a judge served as a prosecutor and then the judge, there is no separate analysis or determination required by the court, there is a finding of automatic bias and a due process violation."

Later, Tucker wrote, “The public expectation of impartial justice is necessary. The slightest appearance of bias or lack of impartiality undermines the entire judiciary, hence the mandate of not only propriety, but the appearance of propriety.”

Tucker added: “Re-argument before the Pennsylvania Supreme Court would be best to perform the heart of the function of the appearance of justice. Argument only on the past submitted briefs will avoid the unacceptable danger of having the slightest appearance of impropriety."

In the second part of his ruling, Tucker said Abu-Jamal’s lawyers failed to present evidence that Castille had a “significant personal involvement in a critical decision" over Abu-Jamal’s case while Castille was district attorney.

Tucker wrote that Castille’s public statements, news releases, letters, and memos written while he was district attorney and showing his support of the death penalty were insufficient to show that Castille implemented a policy particularly because of Abu-Jamal.

The judge did note that the commonwealth failed to produce two documents it was obligated to preserve while Abu-Jamal’s appeals were active. The unavailability of the documents could be prejudicial to Abu-Jamal, but the commonwealth’s conduct was not egregious, Tucker wrote.

Staff writer Chris Palmer also contributed to this article.