Hundreds of children were sexually abused over a period of at least four decades by priests or religious leaders in the Roman Catholic Diocese of Altoona-Johnstown, a statewide investigating grand jury has concluded.

The findings by the grand jury, released Tuesday by the office of state Attorney General Kathleen Kane, detail widespread abuse involving at least 50 priests or religious leaders. The findings reveal a troubling history of diocesan superiors concealing the child abuse as part of an effort to protect the church's image.

The 147-page report details -- at times graphically -- accounts of sexual abuse of children at the hands of priests and church leaders. The late Monsignor Francis B. McCaa, the report notes, was "a monster" who groped and fondled the genitals of at least 15 boys, many of them altar boys. McCaa was assigned to Holy Name Church in Ebensburg for more than 20 years.

At least one of his victims committed suicide, the investigation found.

The grand jury found the case of Joseph Gaborek, 70, to be "particularly heinous example of the Diocese exercising authority and influence to cover up the sexual abuse of a child at the hands of a Diocesan priest."

Gaborek, who was assigned to St. Michael's Church in West Salisbury and St. Mary's Church in Pocahontas in the early 1980s, sexually violated a boy after recruiting him to work at the parishes, according to the report.

Monday's report is the latest case in the global sexual abuse scandal that has rocked the Roman Catholic Church worldwide. The repercussions of that scandal in the United State has driven parishioners from the church, forcing parishes in some communities to shutter their doors amid dwindling attendance.

Allegations of sexual abuse by priests in the Altoona-Johnstown diocese, and allegations that diocesan officials ignored or covered up reports of abuse, have been reported by various news media for decades.

Similar allegations of child sexual abuse at the hands of priests have been made across scores of diocese in the U.S., from the largest to the smallest in recent decades.

Few have been as stunning as the scandals that played out in Boston, the fourth-largest diocese, and Philadelphia.

In Boston, after decades of allegations and investigations, church officials in 2003 agreed to pay $85 million to settle more than 500 civil suits accusing priests of sexual abuse and church officials of concealment.

"Spotlight," the film that on Sunday won the Oscar for best picture Sunday, is the story of the Boston Globe's investigation of the allegations of sexual abuse and cover up in the Boston diocese.

And in Philadelphia, in the wake of a 2011 grand jury report that found widespread clergy sexual abuse and concealment by church officials, the diocese has removed a number of priests deemed unsuitable for the priesthood. Philadelphia also resulted in the conviction and sentencing of Monsignor William Lynn, the highest-ranking U.S. Catholic Church official convicted in a child sex abuse scandal.

Monsignor William Lynn walks from the criminal justice center after a bail hearing in January in Philadelphia. Lynn, a Roman Catholic priest who recently won an appeal of his landmark conviction in the priest-abuse scandal, was released from prison last week, but must remain on electronic monitoring while prosecutors ask the state Supreme Court to restore the conviction. (AP Photo/Matt Rourke)

A Pennsylvania appellate court recently ordered a new trial for Lynn, overturning for a second time his landmark verdict. A three-judge Superior Court panel found that Lynn's 2012 conviction had been tainted by prosecutors' presentation of nearly two dozen examples of the Philadelphia Archdiocese's failure to handle pedophilia within its ranks.

A 2014 study commissioned by the Catholic Church found that more than 4,000 U.S. priests had faced sexual abuse allegations in the last 50 years. The cases involved more than 10,000 children - mostly boys.

Between 2004 and 2013, the Catholic Church spent more than $2 billion in a settlements, therapy for victims, support for offenders and attorneys' fees with regards to clergy sexual abuse.

Tuesday's grand jury report detailed accounts of abuse by Martin Cingle, 69, a priest who in 1979, groped the genitals of a child while sleeping next to the boy on a cot in his underwear.

In a two-year exhaustive investigation, the grand jury reviewed more than 200 exhibits and heard testimony from numerous witnesses, ultimately executing a search warrant last August at a diocesan office, where officials uncovered a "secret archive."

Pope Francis in 2014 created the Pontifical Commission for the Protection of Minors to advise him in the fight against child sexual abuse has reiterated that Catholic bishops have "a moral and ethical responsibility" to report suspected abuse to civil authorities. In this photo taken in September 2014, Francis celebrates Mass at Cathedral Basilica of Saints Peter and Paul in Philadelphia. James Robinson, PennLive.com

Found within boxes and filing cabinets detailing the sexual abuse of children, authorities found internal correspondence related to the sexual abuse, including handwritten notes of Bishop James Hogan and letters and documents sent to Bishop Joseph Adamec. Investigators removed approximately 115,042 documents from the diocese office.

Investigators used the materials to detail the actions of Hogan and Adamec, who led the Altoona Diocese from the mid-1960s through 2011. The bishops were at the forefront of the cover-up, the grand jury noted in its report.

Kanes said diocesan officials endangered thousands of children and allowed known child predators to abuse additional victims.

"The heinous crimes these children endured are absolutely unconscionable," said Kane, speaking at a press conference at the Blair County Convention Center. "These predators desecrated a sacred trust and preyed upon their victims in the very places where they should have felt most safe."

Kane said the cover-up carried out by clergy leaders, which allowed the abuse to continue for decades, was equally troubling.

"They failed in our society's most important task of protecting our children.

Although the investigation is ongoing, none of the criminal acts detailed in the grand jury report can be prosecuted due either to the deaths of alleged abusers and the statute of limitations, which in most cases, has expired.

Additionally, the grand jury deemed that "deeply traumatized victims" were unable to testify in court.

The grand jury has issued recommendations, including lifting the statute of limitations for sexual offenses against minors and urging the Legislature to suspend the civil statute of limitations on sexual abuse claims.

The grand jury also found several instances in which law enforcement officers and prosecutors failed to pursue allegations of child sexual abuse within the diocese.

In the case of Gaborek, for example, investigators found that Bishop Hogan assured police investigators that he would send the priest to "an institution." Gaborek was sent on sabbatical to a school for boys where no psychological or psychiatric treatment was provided. Gaborek was later reassigned to another parish.

The diocesan files detail Hogan's intervention in the police investigation. One of the files notes that Gaborek "would have been prosecuted and convicted of [sexual contact with a 16-year-old boy] except that the bishop intervened and he was sent to Michigan for treatment and then placed in another parish upon his return."

In the case of Cingle, the files show that the alleged 1979 victim met with Bishop Adamec in 2002. The bishop sent the young man for "treatment," which lasted one month. The diocese, the files show, found no evidence of "psychopathology in the psychological data" with regards to the priest. Cingle was returned to full-time ministry.

During his testimony before the grand jury, Cingle acknowledged that he could have accidentally fondled the boy's genitals. Cingle, the report stated, told Adamec the same version of the story, but the account does not appear in diocesan records.

Cingle was removed from the ministry last year at the urging of the Office of Attorney General. Investigators concluded that Adamec wanted to avoid scandal. The matter was never reported to law enforcement.

In the case of McCaa, the grand jury found that he had abused children during confession; other times, he abused his victims while they were standing together.

Hogan kept detailed notes of his meetings with two prosecutors who worked for the Cambria County district attorney's office, the report states. The bishop transferred McCaa to work as a chaplain at a West Virginia hospital.

The Diocese of Altoona-Johnstown covers an eight-county region that includes Bedford, Blair, Cambria, Centre, Clinton, Fulton, Huntingdon and Somerset counties. More than 90,000 parishioners are members of the diocese.

In a report last year, the United States Conference of Catholic Bishops found that between July 1, 2012, and June 30, 2013, a total of 857 people came forward in 191 Catholic dioceses and eparchies to make 936 allegations of sexual abuse.