But the day never came.

Now, 40 years after the shocking murder of Denise McGregor, Colleen hopes to one day receive a phone call advising her the killer has been found.

“I await that phone call,” the 56-year-old said.

“I certainly hope it happens in my lifetime.”

Colleen and her siblings Shane, Denise and Sharon grew up in Penshurst.

The siblings and their mother moved to Melbourne after their parents Cedric and Carmel split up.

“Mum was a nurse and she got a job back in Melbourne,” Colleen said.

“She used to work there and come home (to Penshurst) on her days off. After about a year we all moved to Melbourne.”

Carmel worked night shift and Colleen would usually prepare dinner for her siblings.

However, on Tuesday, March 20 in 1978, she wasn’t home.

“I was out with my boyfriend, who later became my husband,” she said.

“We took his mum over to see his brother.”

Colleen’s younger sisters were asked to pick up takeaway from a nearby shop.

Sadly, Denise would never return home.

A short distance from home Denise told Sharon to go ahead because she wanted to pop into a nearby milkbar.

Colleen arrived home about 11pm to find her mother frantic with worry.

“Mum told me Denise was missing, she had already called the police.”

Colleen remembers the family jumping in the car and driving around in search of Denise.

“We drove all around the streets and knocked on doors – to no avail,” Colleen said.

“I think we drove around until 3 in the morning.”

Denise’s body was found the next morning, about 12 kilometres from their home on the side of the road.

The 12-year-old had been brutally raped and murdered.

The murder sent shockwaves through the community – it was a time when parents wouldn’t think twice of allowing their children to go to a nearby shop on their own.

“You weren’t scared, it was a different era,” Colleen said.

The day after Denise’s disappearance, Colleen was watching television with her boyfriend’s mother when a news report flashed up.

“They said they had found a schoolgirl,” Colleen said.

“His mum turned and said ‘it won’t be your sister’.”

But Colleen knew deep down it was.

She returned home and the news they had all been dreading was confirmed.

Colleen remembers talking to police after the murder and answering calls from Denise’s school friends.

“I would have to say ‘sorry Denise is dead’.”

Over the years, police have contacted the family on numerous occasions to advise of possible new leads in the cold case.

Sadly, the killer remains at large.

However, Colleen holds out hope justice will be served and DNA from the crime scene will lead to an arrest.

She believes there is someone who knows something about her sister’s murder that could deliver closure to her family.

“There will be a little link somewhere,” Colleen said.

“Even if it’s just a memory or something similar that happened to someone, even the smallest thing might help.”

Colleen said not a day goes by when she doesn’t think about her sister.

She describes her as a friendly girl who “talked to anyone and everyone”.

She was well-known in Penshurst, taking over her brother’s newspaper delivery round when he finished.

Colleen said her sister loved listening to music.

“I think Andy Gibb was the last record she ever bought,” she said. 

Colleen said her mother talked about Denise all the time and even started a group for people grieving the loss of a loved one.

“She was a very strong woman,” Colleen said.

The death shook Colleen to the core and she still finds herself looking on in fear if she sees a young child out and about on their own.

“Whenever I see a death on the television - if they’re over 58 I wonder if they have a link,” Colleen said.

“I’m always doing my own detective work, hoping.”

Colleen said her mother had been forever grateful for the kind person who paid for her sister’s funeral.

“Mum never knew who it was,” Colleen said.

“I’d just like to say thank you to whoever it was that paid for it.”

Over the years Colleen has stayed in contact with the homicide squad, which to this day is still searching for Denise’s killer. She thanked police for their support over the years.

A $50,000 reward remains in place for information that leads to a conviction.

Colleen said she wanted answers and justice for her sister.

Anyone with information is asked to contact Crime Stoppers on 1800 333 000.