Investigators were serving a search warrant Wednesday morning at the Archdiocese of Galveston-Houston as part of a case against a former Conroe priest accused of molestation.

Multiple files alleging details of child abuse by priests were located by investigators at the Archdiocese of Galveston-Houston on Wednesday, sources tell KHOU 11 Investigates.

The files were found as part of a search of the Chancery. Investigators were serving a search warrant as part of a case against a former Conroe priest arrested for molestation earlier this year.

The unprecedented action in Texas was taken by the Montgomery County District Attorney’s Office, along with the Texas Rangers and Conroe Police Department. More than 50 investigators arrived Wednesday morning carrying boxes inside the Chancery, located at 1700 San Jacinto Street in downtown Houston.

The DA’s office said investigators were looking for documents in connection to the criminal case of Father Manuel LaRosa-Lopez, the priest charged in September on four counts of indecency with a child. In the search warrant filed Wednesday, the DA’s office sought to examine confidential documents held in the Archdiocese’s Chancery and secret archives.

Montgomery County District Attorney Brett Ligon said in a news conference Wednesday if the search turned up documents about potential criminal activity involving other priests, the Texas Rangers would investigate that information.

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“This is not a search warrant against the Catholic Church,” Ligon said. “It’s a search warrant to get evidence about (La Rosa-Lopez). ... If there's something to be covered up, I'm sure I'll find it. And whether it's a thumb drive or it's a pick-up truck or whether it's a DPS van full of stuff, we're going to take everything we believe is pertinent to our case."

The Archdiocese addressed the secret archives in a statement, calling “’secret archives’ a Church term pertaining to confidential documents kept in a secure manner for the protection of the privacy of individuals – not unlike medical records.”

Ligon said he spoke with Cardinal Daniel DiNardo, who oversees the Archdiocese of Galveston-Houston, Wednesday morning and he’s cooperating with the investigation. DiNardo didn’t know about the search beforehand, Ligon said.

The Archdiocese of Galveston-Houston said it's fully cooperating with the investigation.

"The Archdiocese of Galveston-Houston continues to cooperate, as we have since the outset, with this process. In fact, consistent with Cardinal DiNardo's pledge of full cooperation, the information being sought was already being compiled," the Archdiocese's statement said. “Pending additional information or developments, the Archdiocese will have no further comment on this ongoing investigation.”

Ligon said that cooperation hasn’t been as open and transparent as he would like. Rather than getting the keys from day one, Ligon said he had to get attorneys involved and obtain a search warrant.

“That’s not the type of cooperation I would hope for,” the DA said. “But it’s the type of cooperation I would expect from a sophisticated company.”

Ligon hopes to have the search completed today, though the investigation into La Rosa-Lopez will continue.

BREAKING: Investigators raid Archdiocese of Galveston-Houston, looking for clergy sex abuse records in “secret archives” retained in Chancery #KHOU11 Investigates pic.twitter.com/7YDm6dALde — Jeremy Rogalski (@JRogalskiKHOU) November 28, 2018

“We’re treating the Catholic Church the same way we treat a bank that has records, the same way we treat a criminal enterprise,” Ligon said.

And if the investigation takes him to the Vatican, “I’ll be heading to Rome,” he said.

This is the fourth search warrant executed for documents pertaining to La Rosa-Lopez. A man and a woman claimed they were abused as teenagers by him between 1998 and 2001 at the Sacred Heart Catholic Church in Conroe.

Since his arrest, authorities executed search warrants at Sacred Heart, St. John Fisher Catholic Church in Richmond, where La Rosa-Lopez was a priest until his arrest, and the Shalom Center in Splendora. The center is a treatment facility where La Rosa-Lopez spent time in 2001 after his first accuser came forward.

Both people accuse Cardinal Daniel DiNardo, who oversees the Archdiocese of Galveston-Houston, of not doing enough to stop La Rosa-Lopez. One of them said DiNardo promised her that the priest would be removed from any contact with children, only to later discover that La Rosa-Lopez remained in active ministry at St. John Fisher Church.

The Archdiocese previously said that La Rosa-Lopez denied the allegations in the criminal charges. The church claimed it notified Child Protective Services after his first accuser came forward, but in court records, police stated they were never able to locate such a report.

La Rosa-Lopez is currently free on $375,000 bond and is due back in court on Jan. 10, 2019.

Additionally, a Pennsylvania federal prosecutor last month put Cardinal DiNardo on notice, in his capacity as President of the U.S. Conference of Catholic Bishops, to preserve all sexual abuse-related documents at any Catholic diocese across the country.

Digital reporter Matt Keyser and investigative producer Tina Macias contributed to this story.