About 170 WA institutions have been reported to the royal commission into child sexual abuse, which has held 161 private sessions in the State and will start its first public hearing in Perth on Monday.
Harrowing details of the torture and abuse of children at four WA Christian Brothers' homes from the 1940s to the 1960s are expected to be exposed at the Perth hearing of the Royal Commission into Institutional Responses to Child Sexual Abuse, which could run for up to three weeks.
Witness lists are yet to be released but 11 former residents of the Castledare Junior Orphanage, St Vincent's Orphanage Clontarf, St Mary's Agricultural School Tardun and Bindoon Farm School are expected to tell their stories of abuse.
Former brothers of the Catholic-run homes are also expected to be called to give evidence about the response to complaints of abuse and WA authorities are also scheduled to be called to provide details on redress schemes.
Another two WA case studies will be investigated by the royal commission at separate public hearings scheduled next month, but the details of the examinations are yet to be announced.
The commission has also scheduled "many more" private hearings, which is one of the sources of the approximate 170 WA institutions which have been reported to the inquiry.
Perth Archbishop Timothy Costelloe released a letter to the Catholic community on Thursday expressing the shame and horror of the abuse which had "infected" the Church and conceding it had "failed terribly" in its responses in the past.
Archbishop Costelloe's sentiments were echoed by Francis Sullivan, the head of the Truth, Healing and Justice Committee set up by the Catholic Church to work with the commission.
Mr Sullivan, in Perth to attend the public hearing, said the damage to the Catholic Church as a result of sexual abuse of children, its failure in handling the issue and the "cover-up" of crimes was "massive". He said the stories which would emerge at the Perth hearings next week could not be described as anything but "horrific tales of misery and abuse".
The commission will report on the three Perth case studies and provide an interim report by June 30 on what it has done and the scope of its task and future work.