Cheryl Grimmer's "horrific" last hour before she was murdered almost 50 years ago.

The brothers were seven, five and four when she went missing.

Ricki, Stephen and Paul returned to the beach from the showers to tell her their mum three-year-old Cheryl was not doing what they asked. She wouldn’t come back with them from the change-rooms. She was three years old, had a mind of her own, what could they do?

The wind had changed. It was 1970 and it had been a scorching January day on Fairy Meadow Beach on the NSW South Coast. The southerly had finally arrived; rain was coming. Their mum, Carole, was 26 and picking up the towels. Her husband Vince, then 24, was away with the army. She’d asked the boys to wash off and went to find her youngest.

Carole was probably thinking about what to cook for dinner. How long it would take to get the kids home, showered and in bed; maybe she could have an hour to herself to write to her mother or her father or her friends in England. They'd moved to Australia from Bristol the year before and were only just settling into their beach-side cottage in Wollongong, New South Wales.

Maybe she didn't panic when she couldn't find Cheryl in the change-rooms. Perhaps she was outside, going back down to the beach. Maybe she was covering herself with even more sand. Surely, there would be a commotion if something horrible had happened?

Carole's search turned into something bigger after 4pm, when lifeguards urged her to call the police.

A massive operation begun. Teams of police and volunteers combed the area for three-year-old Cheryl, who wasn't on the beach, wasn't with her brothers, wasn't building sandcastles. Vince came back from the army to join the search. The family would never be the same again.

Cheryl had disappeared and her body was never found.

Now, nearly 50 years later, a 63-year-old man has been arrested and charged with the murder of Cheryl Grimmer in 1970.

Police have said Cheryl died within an hour of the abduction and the offences - which will emerge in court - were “quite horrific”.

The man, who has not been identified, was reportedly 16 at the time of Cheryl's disappearance. Several witnesses reported seeing a teenage boy around 180cm tall, with fair skin, of a medium build, with brown hair and blue eyes "loitering" around the surf club pavilion. This breakthrough came at the end of last year; it was never discovered in the initial investigation.

"He was seen here in the morning and the afternoon," Detective Inspector Ainsworth told The Sydney Morning Herald in December last year.

The case was re-opened and, in January, police asked for help locating former staff and residents of the Mount Penang Training School - a juvenile justice centre for troubled boys. It was said someone associated with the school "might have valuable details about the case".

On Wednesday, in the beachside suburb of Frankston in Melbourne, a man was arrested under suspicion of his involvement in Cheryl's disappearance. Police are extraditing him to NSW where is due to be charged today.

"What do you say? What do you do? It's affected me all my life," Cheryl's eldest brother, 54-year-old Ricki Grimmel, who was seven at the time of her disappearance, said last year when the police re-opened the case.

Ricki cried, got angry. When asked by reporters if he's ever forgiven himself, he replied: "Never, ever. I never will. Everybody says, 'It wasn't your fault' but come and stand where I am standing and see what it feels like," he said.

"Just let us know where she is. Give us something we can go and mourn. It's horrible. Stop it. It's cost me my family and everything."

Cheryl was declared dead in May 2011 by a coroner. There was no body. A coroner's report. Cold papers and black-and-white typeface, plus 41 years of not knowing anything, was what it took for Cheryl's life to officially end.

Stephen Grimmer, 52, said the brothers have never stopped looking for their little sister.

"You never get over it," Stephen, 52, also faced the media in December last year. "I ride past [Fairy Meadow beach] all the time and I always look … so it's always on my mind."

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'Hell' is too simple a word for what this family has been through.

Shortly after her disappearance, there was a note demanding ransom for Cheryl's return. Police, undercover as council workers, surrounded the drop-off point. Nothing eventuated.

After this, a local man made a confession. He said he killed Cheryl but, after investigation, police deemed the confession false.

In 2012, a woman came forward thinking she might be Cheryl. She undertook a DNA test. It, too, came back negative.

In 2016, the brothers recreated the crime scene for police officers at Fairy Meadow Beach — as if they hadn't replayed it in their heads one million times over.

Ups and downs and around and around. No closure. False hope in between the devastation of it all.

Carole and Vince returned to the UK 10 years after Cheryl went missing. They couldn't stand to be the parents of the 'girl who put Illawarra on the horror story map'.

Carole refused to believe Cheryl was dead, even after the coroner's finding, offering a $100,000 reward for any information about her whereabouts. Both parents died without knowing what happened to their baby girl.

The brothers are still suffering. But hopefully this time, the result will be different.

Hopefully this 63-year-old man holds the answers, however horrible. Hopefully a police charge, a trial, a prosecution might offer some closure. Something more for Ricki, Stephen and Paul to hold onto, grieve properly and maybe even move past. They've waited too long for the truth.