NEW YORK — A Pennsylvania appeals court on Thursday overturned the child-endangerment conviction of a Roman Catholic official, upending a landmark court case that had found a senior church member guilty of covering up sexual abuses by priests under his supervision.
The unanimous decision by the Superior Court in Pennsylvania dismissed the criminal case against Monsignor William J. Lynn, who had been sentenced to three to six years.
In the ruling, state Superior Court judges said there was not sufficient evidence to prove that Lynn, 62, had intended to “promote or facilitate” acts of child endangerment, and they ordered his release from prison.
The Philadelphia district attorney, R. Seth Williams, said Thursday that he strongly disagreed with the decision and planned to appeal. ‘‘Because we will be appealing, the conviction still stands for now, and the defendant cannot be lawfully released until the end of the process,’’ Williams said.
Pending the appeal, the Superior Court made no decision on bail for Lynn, sending that matter back to the trial court.
Lynn was convicted in June 2012 after prosecutors charged that he had reassigned priests who preyed on children to new parishes in Philadelphia when he was secretary for clergy. The conviction stemmed from a case against a priest, Edward V. Avery, who was transferred despite a complaint of sexual abuse.
During the trial, prosecutors presented evidence that Lynn had concealed information from the public to avoid bad publicity and lawsuits. Lynn’s lawyer argued that the state’s child-endangerment law at the time applied only to parents and caregivers, not to supervisors like Lynn.
“I felt all along that the trial was a freight train,” said Jeffery Lindy, Lynn’s lawyer for the trial. “None of the judges who had this case wanted to stand in the way. It was too bad politically.”
The single guilty verdict in the trial was widely seen as a victory for the Philadelphia district attorney’s office, which had been investigating the archdiocese since 2002.
It was hailed by advocates for abuse victims who have argued for years that senior church officials should be held accountable for concealing evidence and failing to act against predatory priests. Lynn was acquitted of conspiracy and a second count of endangerment.
The three-month trial cast a harsh light on the leadership of the archdiocese, especially Cardinal Anthony J. Bevilacqua, whom Lynn advised.
Archbishop of Philadelphia from 1988 to 2003, Bevilacqua died in January 2012, but his name was invoked frequently during testimony in Lynn’s trial. Lynn’s lawyer told the jury that “in this trial, you have seen the dark side of the church.”
As secretary for clergy in the archdiocese from 1992 to 2004, Lynn recommended priest assignments and investigated abuse complaints. Prosecutors presented a flood of evidence that he had not done enough to keep suspected molesters away from children, let alone to report them to law enforcement.
But the length of the jurors’ deliberations and the mixed verdict showed the difficulty of placing criminal blame on one church official. The jurors also wrestled with the definition of conspiracy and with the question of criminal intent on the part of Lynn.
The trial judge, M. Teresa Sarmina, had rejected the argument of Lynn’s lawyers that the child-endangerment law at the time applied only to parents and caregivers.
Sarmina said Lynn perhaps drafted a 1994 list of accused priests to try to address the clergy abuse problem. But when Bevilacqua had the list destroyed, Lynn kept quiet, she said. A copy of the list was found years later in a safe and was discussed at trial.
In sentencing Lynn, Sarmina had said the church administrator had ‘‘enabled monsters in clerical garb . . . to destroy the souls of children,’’ rather than stand up to his bishop.
Lynn told the judge: ‘‘I did not intend any harm to come to [the boy]. The fact is, my best was not good enough to stop that harm.’’
Supporters believe Lynn was made a scapegoat for the church’s mistakes. Nonetheless, his attorney, Thomas Bergstrom, said Lynn hopes to return to ministry, the Associated Press reported.
He has had the support of the current Philadelphia archbishop, Charles J. Chaput, who twice visited him in prison.
The archdiocese said in a statement that its handling of abuse complaints ‘‘has changed dramatically since the events over 10 years ago that were at the center of the trial.’’
Over the past two years, Chaput has turned over sex-abuse complaints to prosecutors and ousted at least nine accused priests from ministry, while restoring others to their jobs after finding complaints unfounded.
Lynn had left the archdiocesan hierarchy for parish work after he was featured prominently in a damning 2005 grand jury report into priest abuse. Lynne Abraham, the district attorney at the time, concluded that too much time had passed to charge anyone criminally.
Williams, her successor, revisited the issue when new accusers came forward under new laws that extended the time limits and added church or school supervisors to the list of people who could be charged.