Investigators in Colorado released a report on Wednesday on child sex abuse by Roman Catholic priests that chronicled the abuse of 166 children at the hands of 43 priests across the state since 1950, with most of the acts committed by just five priests who abused 102 children.

But the investigation was criticized by victims’ groups. They called it toothless and faulted its reliance on the voluntary participation of the Roman Catholic Church, which the report itself accused of a decades-long effort to hide potentially criminal activity from parishioners and the authorities.

The report said that instances of abuse peaked in the 1960s and 1970s, but investigators said that because of shortcomings in church record-keeping and reporting practices they could not be sure the abuse was not continuing today.

“Arguably the most urgent question asked of our work is this: Are there Colorado priests currently in ministry who have been credibly accused of sexually abusing children?” the report said. “The direct answer is only partially satisfying: We know of none, but we also know we cannot be positive there are none.”