Tributes have poured in for Anthony Foster, who dedicated his life to seeking justice for victims of child sex abuse at the hands of the Catholic Church.
He is believed to have died from a major stroke after falling and hitting his head on Friday night. He was 64.
Mr Foster became a relentless advocate after his daughters, Emma and Katie, were raped by notorious abuser and pedophile Father Kevin O'Donnell at their Melbourne primary school between 1988 and 1993.
Mr Foster and his wife, Chrissie, shared their torment to the media and the Royal Commission into Institutional Responses to Child Sexual Abuse.
Their daughter Emma took an fatal overdose of medication in 2008, and Katie was hit by a car after binge drinking in 1999, leaving her brain-damaged and in need of 24-hour care.
Many have described Mr Foster as a voice for survivors who struggled to discuss their personal experiences.
"Anthony was the person that stood up and he spoke in quiet but powerful words and in many ways you know, he roared like a lion on this issue," friend and ABC journalist Paul Kennedy said.
Mr Kennedy co-authored a book, Hell on the Way to Heaven, with Mrs Foster in 2010.
"It is just so sad for everyone that Anthony Foster has died," he said.
Royal commission chairman Justice Peter McClellan praised the family's dedication to achieving justice for child sex abuse survivors and said he was "deeply shocked and saddened" by the news.
"They attended hundreds of days of public hearings and participated in many of our policy roundtables," he said in a statement on Saturday.
"With a dignity and grace, Anthony and Chrissie generously supported countless survivors and their families whilst also managing their own grief."
Francis Sullivan, the chief executive of the Catholic Church's Truth Justice and Healing Council, said Mr Foster was a man who put the interests of his daughters and the many survivors he worked with first.
"Anthony's strong and clear advocacy and support will be missed by many," he said.
The Fosters received $750,000 in a settlement with the Melbourne Archdiocese in 2006 after spending 10 years pursuing compensation for the abuse of their daughters.
But their name became prominent in early 2016 after Mr Foster accused Cardinal George Pell of stalling to improve the Melbourne Response scheme, which is supposed to help victims.
Fellow advocate Manny Waks voiced his anger with the Catholic Church for the "ongoing pain and suffering they caused the Fosters" and said the family should be publicly acknowledged for their "incredible work".
"Despite all they endured, they maintained determination and dignity in their ongoing campaign for justice and reform within the Catholic Church - for them and for others," he wrote on Facebook.
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