PHILADELPHIA — The landmark conviction of a Roman Catholic church official imprisoned over his handling of abuse complaints in Philadelphia was overturned Tuesday for the second time.

The state Superior Court ruling awarded a new trial to Monsignor William Lynn, who has been on a legal roller coaster since his 2012 trial on child endangerment charges.

The appeals court said the trial judge erred in allowing about 20 other victims of sex abuse by clergy to testify about how their complaints were handled by the Archdiocese of Philadelphia. The judges said the trial court "abused its discretion by admitting a high volume of other-acts evidence."

Lynn was convicted of endangering a boy who said he was assaulted by two priests and a teacher, including a previously accused priest who was transferred to his parish.

The 64-year-old has been back in prison since April, after the conviction overturned in 2013 on different grounds was reinstated by the state Supreme Court.

"It's certainly taken a toll, but he's holding up," said defense attorney Thomas Bergstrom, who visited Lynn last week and hopes to get him released quickly. "It's a roller coaster, and he's been on it. Hopefully, we can end it now."

Lynn, the secretary for clergy in Philadelphia from 1992 to 2004, has now served about two years of his three-to-six year term.

Philadelphia prosecutors, who could again seek reinstatement, said they were reviewing the latest decision in Lynn's case, which they called a violent crime.

"The Philadelphia District Attorney's Office is committed to protecting all the citizens of Philadelphia against crimes of violence such as those committed by Monsignor Lynn," the office said in a statement.