U.S. prosecutors pursuing an unprecedented inquiry into clergy sex abuse and cover-ups within the Catholic Church in Pennsylvania have turned their attention to bishops outside the state, signaling a wider federal probe than initially reported.

In a letter sent this month, Philadelphia-based investigators instructed the U.S. Conference of Catholic Bishops, its staff, and the nearly 200 prelates across the country who comprise its membership to preserve personnel records and documents related to sex abuse that could be of interest to the probe.

A conference spokesperson declined to describe what types of records the prosecutors sought to preserve, but conference general counsel Anthony R. Picarello Jr. said Friday that his organization had complied.

"We have transmitted the U.S. attorney's letter [to our staff] at his request, and in the spirit of cooperation with law enforcement," he said in a statement.

News of the correspondence comes less than three weeks before the U.S. Conference and its members are set to convene in Baltimore after months of developments that have plunged the church into crisis over its handling of sex-abuse claims.

The last three months have seen the toppling of Cardinal Theodore McCarrick of Washington and his successor, Donald Wuerl, over abuse-related complaints as well as a scathing Pennsylvania grand jury report that implicated six of the state's eight Catholic dioceses in decades of concealment, and inspired similar probes in at least a dozen other states.

But until this month, the bishops had largely escaped federal scrutiny.

All eight Pennsylvania dioceses confirmed last week that they had been served on Oct. 9 with grand jury subpoenas from prosecutors under the purview of William M. McSwain, U.S. attorney for the Eastern District of Pennsylvania.

McSwain's letter to the U.S. Conference – first reported by Rocco Palmo, a Philadelphia-based writer of the Vatican insider blog Whispers in the Loggia — was sent on the same date and was distributed by the conference to dioceses across the country earlier this week.

Archdiocesan spokespeople from across the country — including in Louisville, Chicago, Los Angeles, and New Orleans — confirmed Friday that they had received the message but said their offices had not been subpoenaed. The letter did not compel the organization or any particular diocese to hand over any information to federal authorities, although it ordered recipients not to "destroy, discard, dispose of, delete, or alter" any of the identified records.

"The practice in the Archdiocese of New Orleans is to always cooperate with any civil investigation," said Sara McDonald, a spokesperson for the Louisiana archdiocese.

Meanwhile, agents already have begun fanning out across Pennsylvania to begin interviewing potential witnesses.

Michael McIlmail, who recently settled a lawsuit against the church after his late son said he was abused by a priest at a Northeast Philadelphia parish in the '90s, said he met with prosecutors assigned to the probe.

"The feds have the resources," he said Friday. "And what I like about the FBI is, if you lie to the FBI, it's a crime."

A spokesperson for McSwain's office has refused to confirm or deny the existence of an investigation. But sources familiar with the matter, although not authorized to discuss it, have said agents are looking at potential crimes ranging from possession of child pornography to aiding and abetting child exploitation and transporting children across state lines for the purposes of engaging in sex.

The subpoenas served on Pennsylvania's dioceses sought records pertaining to church finances, clergy assignments, insurance coverage, and confidential personnel files that have come to be known as the church's secret archive.

News of similar inquiries by federal prosecutors in Washington and Buffalo, N.Y. also emerged this week.

Staff writer Craig R. McCoy and Liz Navratil of the Harrisburg Bureau contributed to this article, as did Peter Smith of the Pittsburgh Post-Gazette.