Child abuse commission reaches ACT

More shocking stories of child sexual abuse are expected to surface during royal commission hearings in Canberra, with the Catholic Church issuing advanced warning.

Five former Marist College students will recount their experiences when the Royal Commission into Institutional Responses to Child Sexual Abuse reaches the nation's capital on Tuesday.

Ahead of the nine-day hearing schedule, the Archbishop of Canberra and Goulburn Christopher Prowse has written an open letter to parishioners.

"Many of you will be shaken by these horrendous stories," he wrote, before offering an apology to abuse victims.

The hearings will focus on the response of the Marist Brothers to allegations of child sexual abuse, in particular how it dealt with claims against Brother John Chute and former Brother "ZA".

A string of past and present teachers and senior school and church officials will also step into the witness box, including former Provincial of the Order, Alexis Turton.

Current Marist College headmaster Richard Sidorko said the school supports and has fully co-operated with the commission.

Evidence has been heard across Australia at a combination of public and closed hearings.

The commission is scheduled to make a final report to the government in late 2015.