Egg donor and surrogate Melissa Sharman has helped bring 22 children into the world - selfless acts that have transformed the lives of families across Australia.

But behind that extraordinary generosity lies a story so dark it has taken her nearly two decades to find the courage to tell it.

Melissa was just 15 when she met notorious child killer Brett Peter Cowan - the man who would go on to murder 13-year-old Daniel Morcombe - at the Sunshine Coast church she attended with her family.

He was 30 and engaged to another churchgoer. Melissa would see him around while volunteering on the video team. He often sat beneath the stage with the students, but she never thought much of it.

What the teenager did not know was that Cowan already had a disturbing history as a convicted sex offender and had spent years in and out of trouble before being welcomed into their close-knit congregation.

Church elders, however, were aware of his violent past.

Yet despite knowing he was on parole and attending a sexual offenders' program, Melissa claims no one warned her and, even more horrifyingly, she was paired up with Cowan for volunteer work, giving him the perfect opportunity to prey on the vulnerable teenager.

'He was the nephew of church elders and the church took him in to "save" him,' Melissa told the Daily Mail.

'We were assigned to a volunteer group with another older woman and were supposed to car-pool to the event, but when he arrived, the other woman wasn't there.

'He was dressed in work clothes and said he needed to change and drove me to his home - a granny flat in a garage - and went to shower.'

Feeling increasingly uncomfortable, Melissa flicked through a magazine on his desk, willing him to hurry up so they could leave.

But when he appeared in the doorway, a canary yellow towel wrapped around his waist and steam billowing behind him, she immediately sensed something was wrong.

'He had this look in his eyes, I can't really explain it, it was sort of numb,' she said.

'He came straight for me, kissed me and tried to pull my clothes off while we fought.'

As Cowan clawed at her clothes, Melissa says she drove her knees into his thighs, momentarily throwing him off balance.

'His towel dropped and as he bent down to pick it up I ran to the door,' she said.

She hid in a nearby sugarcane field, terrified he'd come after her, before calling a friend to come and collect her.

'I told a friend, she told another,' she said.

'The pastor heard about it and called me to his office to see him, listening and promising he would take care of it, before he swept it under the rug.

'This was fine with me. I felt humiliated and wanted it all to go away.'

Melissa continued seeing Cowan at church over the following months, his arm draped around his fiancée and a smug expression on his face.

Eventually, she stopped attending altogether and her life began to spiral, getting in trouble at school and at home.

Five years later, Cowan struck again, this time luring a young boy in a red T-shirt from a Sunshine Coast bus stop.

The abduction and murder of Daniel Morcombe on December 7, 2003, shocked the nation. It was two weeks before his 14th birthday and only weeks before Christmas.

The teenager had been waiting for a bus to the shops to get a haircut and buy Christmas presents for his family when, unbeknown to him, the bus broke down before reaching the stop.

Cowan drove past the broken-down bus, spotted Daniel standing alone and seized his opportunity.

When the schoolboy failed to return home that evening, he was reported missing by his devastated parents.

Days turned into weeks, and weeks into months, with no sign of Daniel.

By then Melissa was working at a supermarket and would occasionally see Daniel's mother Denise shopping there.

'I could see the sadness in her eyes,' she recalled. 'I remember thinking someone knows something and they should speak up.'

What she did not realise was that someone was her.

Years later, Melissa came across artist impressions linked to the investigation online.

'I recognised the sketches on the Crime Stoppers website but I couldn't place why.

'Kind of like when you see someone in a public place and you're trying to remember where you know them from.

'I called Crime Stoppers and said, "I think I know who this is, I don't know for sure, but I feel like I'm sure."

'I gave them his name and the way he had spelled it, which was different to how it's spelled now.

'I told them what had happened to me. They took the information and ended the call.'

During the investigation into Daniel's disappearance, police received more than 20,000 leads and 15,000 reports through Crime Stoppers.

But Melissa could not shake the feeling.

She went online and searched for Brett Cowan, eventually stumbling across a church blog.

'I found out everything about who he was and what he had done,' she said.

'I saw the details of his sexual offence charges in Darwin and I just knew it was him.

'The biggest betrayal for me was the church. They knew what he had done and let him in anyway.'

The following day, police interviewed Melissa and, several months later, Cowan was taken into custody and charged with Daniel's murder.

'Police said they didn't know if I would have to testify and that was a tough couple of years,' she said.

'I thought Brett was just a creep from church who couldn't keep it in his pants, but it was pretty devastating when I joined the dots.

'I felt that if I had made more fuss back then, that Daniel's outcome might have been different.

'I carried shame and guilt for a really long time. I often thought that if I had spoken up louder and gone to police instead of my church, that he would have been returned to jail and what happened to Daniel might have been prevented.

'That's a lot for someone to carry. I was a child and the adults in my life that knew what he had done had that responsibility and duty of care.

'After Brett attacked me, my life spiralled. I got into an abusive relationship and was surviving.'

But at 27, something changed and while working as a nurse in a small hospital, Melissa came across an advert in her local paper looking for an egg donor.

'There, a small picture of a stork and baby caught my attention. Mistaking it for a birth announcement, I read the words printed in an elegant italic font.

'I'd never heard of donating eggs before and so I tore out the ad and took it with me.'

'I wanted to do something good. I wanted to give hope to someone that I wasn't feeling myself.'

Since then, she has helped 12 families welcome 22 children via egg donation and surrogacy, and even supports other parents and donors through the process.

'It's something I care deeply about it, even though it was something I stumbled on accidentally.

'When I was in my darkest years, it gave me purpose and hope that I could do something good.

Melissa is still in touch with the families she helped create and says it has given her a sense of purpose

'I know the kids and their parents and there's no secrets. The kids meet up together and quite a few of them are on kids' messenger and Roblox.

'They're really proud of their stories and their parents are lovely people.

'I'm helping others while healing myself.'

Melissa's memoir, The Beauty of Broken Things, is out now.