His devotees call him Little Pebble; his victims know him as a paedophile.
William Costellia Kamm is the self-appointed leader of a notorious doomsday cult that formed its headquarters in 1987, based in a secure compound in Cambewarra, just outside Nowra on the NSW South Coast.
At its height, thousands of pilgrims from around the world travelled to the bush setting for a spiritual experience like no other.
On the 13th day of each month, the Virgin Mary would appear to William - her apparition only visible to him - and he would pass on her messages and warnings to the gathered and devout crowd.
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He declared his compound the Holy Ground, a new promised land for his followers for when the apocalyptic second coming of Christ would wipe out most of mankind.
At the time, Kamm was married and had four children but unknown to his wife, this self-proclaimed Messiah was planning on creating a royal harem, filled with 12 queens and 72 princesses - 84 mystical spouses to bear his children to repopulate the earth.
Little Pebble claimed God chose who his brides would be but as Detective Chief Inspector Peter Yeomans from the State Crime Command puts it, it was Kamm who did all the grooming, and his preference was under-age girls.
"He was using religion in such a way that just split families. So, it was just awful and it continued for many many years. I see it as grooming with the families to get to these children and it's just terrible," he says.
In the Hinrichs family, Kamm found the perfect target. He discovered them on one of his many pilgrimages to Europe where he would drum up business by preaching his particularly conservative and fringe brand of Catholicism, for which he would ultimately be excommunicated by the Church.
Amongst the faithful in Munich, disaffected by the so-called modernisation of the Catholic Church, Kamm found Ingrid Hinrichs and her family of pretty blonde daughters.
This struggling family had already suffered unspeakable abuse. In the attentive Kamm, they believed they had found a benevolent saviour.
For the next few years, flying between Australia and Germany, Kamm was devoted to infiltrating the family, as daughter Stefanie Hinrichs remembers.
"We weren't a wealthy family. So he took us places and it was like, 'Goodness this man is spoiling us'," she says.
Stefanie was just eight or nine at the time. Her older sister, Bettina, was 15 or 16. Kamm was then 41.
"Eventually, when he came back to Germany, he would stay in our little apartment and sleep with my older sister, because at that point it was, 'she's going to be my wife' ... and in the mornings, William would tell (me) to get under the blankets with them both, and at the time I didn't think anything of it," Stefanie recalls.
"It was playful but now when I think about it, it just kind of makes me sick."
When Bettina was 17, Kamm and she celebrated a "mystical" marriage ceremony in Germany before moving to Australia to live in the cult compound in Nowra. Bettina was already pregnant with the first of their six children.
For a supposed holy man, Kamm was surprisingly handy with a ready-made lie or two.
He had told Bettina God had chosen her to be his new wife and mother to his existing four children because his current wife, Ann, would die in the next month or so. Until then he wanted Bettina to pretend she was the Kamm family's new nanny.
That was 1991. Ann saw through the nanny ruse, left Kamm and moved out of the cult with the couple's four children. Happily, she is still alive today.
The rest of the Hinrichs family moved to the cult headquarters the following year, believing they were relocating to heaven on earth.
As Stefanie revealed to 60 Minutes, the move marked the end of her childhood in the most disturbing way.
When she was just 13, Kamm claimed the Virgin Mary had selected her to be one of his new queens.
At first he promised their children would be conceived through immaculate conception - a heaven-sent gift in more ways than one for the young teenager. But very soon after, the Virgin Mary changed her mind and wanted Stefanie to conceive in the "natural" way.
Stefanie was horrified God wanted her to have sex with her sister's husband.
As she was urged to do by Kamm, Stefanie wrote all her fears and secret pleadings to the Virgin Mary in her diary.
It was a master stroke in manipulation. Kamm, pretending to be the Virgin Mary, wrote back, effectively telling the desperate girl there was no way out.
The diaries are filled with anguish and confusion.
A young girl, threatened with damnation, wanting to please God and the Virgin Mary but desperately trying to escape the clutches of her lecherous brother-in-law.
It was a battle Stefanie ultimately won when, some years later as an adult, she finally reported Kamm to police, leading to his conviction and jailing.
Perhaps it was divine intervention but it was her writings as a child, made at the urging of Kamm, that gave police the evidence they needed to nab him.
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