The dark past of the Dunedin diocese and its clutch of clerical paedophiles** still ensnares Marc. But he means to be free of it.

One drunken night in 2013 in Melbourne, Marc* wrote an email to the Catholic Church in New Zealand. He was drunk a lot back then.

"I could drink half a bottle of vodka right now and probably still have a lucid conversation with you," he said. Not now, now he's dry.

He was a functioning alcoholic back then, but still, he couldn't remember sending the email.

"The first line, and this was five years ago, was, 'If there's ever a Royal Commission in New Zealand, I will come back and give evidence'.

"And as I said, I didn't remember writing it, and I got contacted three weeks later by the church and it was a surprise."

He has come back and he has given evidence, in Christchurch recently.

It is his second attempt to get some kind of justice for how he was robbed of his childhood in Dunedin in the 1980s, by four Catholic leaders who sexually violated him for years.

He considers his first attempt to be heard, in 2013, naive. The email he had sent to New Zealand, resulted in a six hour interview with the Christian Brothers in Australia.

He held a lot back, speaking about just one abuser, to test the waters.

"I only did it by myself. I thought that I was strong enough to do it by myself. And you know, keep everyone in check. I thought I was smart enough to know and I realise that that was probably a little bit naive on my part.

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"I thought that it would be an open and honest process to go through and people would look after me and act as my advocate. And I found that they weren't, they were acting as the church's advocate."

The Brothers gave Marc an apology, a payout, and a waiver he signed preventing him ever taking on the church again.

"That is not the way that school life is meant to be, and I apologise for that," the Brothers' 2013 apology reads. "I hope that gradually your unfortunate memories may become less intrusive."

Marc was preyed on from age nine to 14, by three known abusers and a priest who still cannot be named; all four are deceased.

The Christian Brothers Vincent Sullivan and Desmond Fay abused the boy at the same time.

A lay teacher at St Paul's high school, Ian Thompson, who other victims have come forward about, later committed suicide.

Marc's father, brother and grandfather, all died during the time of his abuse.

The men used it as leverage, that they would tell the family he was misbehaving, he said.

"Absolutely. They were going to tell my mum - and my dad was dying. I couldn't come home and tell mum that I was getting in trouble at school.

"I was a very fragile child going through the extended illness of my father. The abuse started the same year that I found out my father was dying."

Four years on, he is sober, is not doing it alone, and has come to New Zealand to tell the full story.

But straight away, he faced more hurdles from the Catholic Church here.

"They had no record whatsoever that I'd made a complaint," he said.

"The investigators had to contact the Australian version of themselves and start asking questions around who I am and my story. So I've had to almost re-prove who I am in New Zealand, even though I felt that I had been reporting my abuse to New Zealand."

He is jealous of what information he provides now, insisting on being told beforehand what will be done with it.

To his dismay, the church told him it would have to split his case up four different ways, between New Zealand and Australia.

"I've already had conversations with the [church] investigators that although I was abused by two Christian Brothers, and there's a priest in there, and there's also a lay teacher, I've told them that they can't split my story up, which is part of what I believe they were going to do.

"My story would go partly to the Christian Brothers, then it would go partly to the Catholic church. And then because there's a lay teacher involved, I'm really in no-man's land with that."

He has asked for the Royal Commission of Inquiry's help to prevent such a split.

However, he believes a unified inquiry into his case could still be derailed, that he might still be forced to tell his story over and again to the likes of the Christian Brothers, who he abhors.

"I've told them that my story must stay together because there's no way that it can be separated. My story has a lot of family tragedy around it. I was losing my father and my brother, and my grandfather died, and were dying through this process ... and these people who were abusing me actually knew of that.

"I hold the church responsible. I see it is as one piece of abuse to me, and separating that out, it doesn't hold the story, it would water it down to a degree ... It was a continual abuse, it was continued traumatisation for me."

Division is one thing, obstruction another: Marc wants the church to outline what the abuse history of the four men was.

"They're saying that they can't give that information to me about other complaints.

"I have given my statement and there's nothing coming back to me saying, 'this person has been previously or a judgement has been upheld, or there has been a number of other abuse cases recorded'."

Despite six years of struggle, and decades of torment, Marc believes he's close to the goal he shares with other survivors.

"That's accountability, accountability [for] the organisation who employed them, protected them."

The Catholic Church's National Office for Professional Standards has been asked for comment.

* RNZ has agreed not to use Marc's surname.

** Comprehensively uncovered by Otago Daily Times reporter Chris Morris.