A few months after she started as operations director for the Archdiocese of Philadelphia's clergy office in 2005, Louise Sullivan was given a task: Straighten up the file room.

The exhaustive grand-jury investigation into alleged sex abuse by priests was over, and the 10th-floor room at the archdiocese's 17th Street headquarters was a mess. Cardboard boxes, files, and papers cluttered the floor.

Atop one corner cabinet, Sullivan noticed a small, locked combination safe. She asked around: Whose safe was it? And what was inside?

No one knew, Sullivan told a Common Pleas Court jury on Thursday.

Her testimony marked the first, albeit small, step in explaining perhaps the most disputed and relevant piece of evidence in the conspiracy and child endangerment trial of Msgr. William J. Lynn, who once ran the office.

Inside the safe was a list Lynn had compiled in 1994 naming 35 active archdiocesan priests who had been diagnosed as pedophiles, had admitted sexual misconduct with minors, or were suspected or accused of such conduct. Who hid it there, why, and who knew are questions expected to get more attention as Lynn's landmark trial begins to wind down.

To prosecutors, the list crystallizes their claim that barely two years into his 12-year tenure as secretary for clergy, Lynn knew the archdiocese was letting dozens of potentially predatory priests work around children.

One of the priests Lynn identified in 1994 as guilty of sexual misconduct was the Rev. Edward Avery. Five years later, Avery sexually assaulted a Northeast Philadelphia altar boy after Mass, an attack that prosecutors contend Lynn had the power and responsibility to prevent.

The monsignor's lawyers say the list is something else — proof that their client, more than any other church official, was trying hard to identify the scope of the abuse problem and address it. Avery was the only priest on the list later accused of assaulting a child, an attack he committed after Lynn had him removed as a pastor and hospitalized, and after Lynn recommended that he work only as a hospital chaplain, not around children.

They also contend that Cardinal Anthony J. Bevilacqua and his top aides were aware of the list and that Bevilacqua ordered all copies shredded in 1994, signs that he understood the breadth of the problem and dictated the archdiocese's response to it. A single copy survived, and it ended up in the safe Sullivan noticed in the file room a dozen years later.

She testified that when no one claimed ownership of the locked box, she hired a locksmith to drill the safe open. Inside was an accordion folder holding manila folders, Sullivan told jurors.

"I casually said to the staff: You all told me there was nothing in there, but here's a file," she testified under questioning from Assistant District Attorney Patrick Blessington.

Sullivan said she didn't review the papers. Instead, she took the entire folder down the hall and dropped it off in the office of an assistant to the priest who succeeded Lynn as clergy secretary, Mgsr. Timothy Senior.

Sullivan said she remembered mentioning her find to Senior, but not any further discussion or what happened to the files.

"At the time, this was a very insignificant task in the office," Sullivan said.

Prosecutors said lawyers for the archdiocese finally turned over the list earlier this year as they prepared for Lynn's trial. That was the first time anyone had discussed the safe with her in six years, Sullivan said.

Among those identified on the list as a having been diagnosed as pedophiles was the Rev. Nicholas Cudemo. Earlier on Thursday, one of his accusers told jurors how Cudemo, her father's cousin, molested her when she was 15 and 16 and attended Archbishop Prendergast High School.

Two decades passed before the woman learned Cudemo had also assaulted her sisters and a cousin, she said. Together, they decided to approach Lynn and other archdiocesan officials in 1991 and press them to remove the priest.

"I really felt for the first time in my life that I was confronting evil," the woman, now a nun who works for the archdiocese, told jurors, "and that we had to do something about it."

Cudemo lost his post as pastor but was ultimately allowed to "retire" and continue celebrating Mass at parishes in the area for more than a decade. Defrocked in 2005, he is one of nearly two dozen priests whose cases are being described for jurors as proof that Lynn's decisions followed a long-standing pattern or practice by church leaders of protecting abusive priests.

Contact John P. Martin at 215-854-4774, jmartin@phillynews.com, or follow @JPMartinInky on Twitter.