PHILADELPHIA (AP):

Federal prosecutors have opened an investigation of child sexual abuse by Roman Catholic priests in Pennsylvania, using subpoenas to demand secret files and testimony from high-ranking leaders in what victims' advocates say is the first such probe ever launched by the US Justice Department.

The subpoenas, served last week, follow a scathing state grand jury report over the summer that found that 301 "predator priests" in Pennsylvania had molested more than 1,000 children over seven decades and that church leaders had covered up for the offenders.

The intervention by the federal government opens a new front of legal peril for the Catholic Church, given that investigations into sexual abuse by clergy members have historically been handled exclusively by state and local authorities.

"It's groundbreaking if we're going to see one of the US attorneys pursuing the Catholic cases," said Marci Hamilton, a University of Pennsylvania professor and chief executive of Child USA, a non-profit think tank focused on preventing child abuse. "The federal government has so far been utterly silent on the Catholic cases."

At least seven of the state's eight Roman Catholic dioceses - Philadelphia, Pittsburgh, Scranton, Erie, Greensburg, Allentown, and Harrisburg - acknowledged receiving subpoenas and said they would cooperate or were working with Justice Department officials.

"This subpoena is no surprise considering the horrific misconduct detailed in the statewide grand jury report," the Greensburg Diocese said in a statement. "Survivors, parishioners, and the public want to see proof that every diocese has taken sweeping, decisive, and impactful action to make children safer. We see this as another opportunity for the Diocese of Greensburg to be transparent."