When Mary Anne Fagan's 3 kids got home after school, they instantly knew something was wrong.

Collins and Mary Anne Fagan had a dreamy life with four happy children and a beautiful home in the family-friendly neighbourhood of Armadale. 

They'd settled in the Melbourne suburb after years of moving around Australia and the UK, during which time Collins was dedicated to building a career in the Royal Australian Air Force. 

While he did that, Mary Anne was busy devoting her own life to their four children as a homemaker. However, in 1978, their family was left shattered by her brutal murder, which remains unsolved 46 years later. 

The morning of February 17 began like any other for the Fagan family. Mary Anne drove her children, then aged 15, 13, 12, six, and one, to school in the family's station wagon. 

She returned home around 9:15 am, with her toddler in tow. A driver passing by saw her chatting away with council workers in the front yard of the family's property an hour later. The group was repairing the road after a main had burst.

The rest of Mary Anne's day wasn't busy. She wanted to put her youngest child, one-year-old Patrick, to bed before she dyed her hair for a birthday party the next day.

Collins, who was at work, made a brief call to Mary Anne around 11am. It would be the last time they ever spoke — in fact, it was the last known contact she had with anyone.

After 4pm, the Fagan children arrived home from school and, upon seeing the side gate open, felt something was terribly wrong. They could hear little Patrick crying inside, and although Mary Anne's car was in the driveway, the doors to the house were locked.

Victoria Police would later say that one of the children raced to search for a phone box where they called their father, while another broke a window to get inside the house. 

They made the grim discovery of their mother's dead body in the front bedroom. She had been bound, gagged and stabbed several times.

According to The Age, Mary Anne still had bleaching cream in her hair. She was lying on top of a plastic sheet, on a bed in one of the bedrooms.

Mary Anne was found by her children after they returned home from school in 1978. Image: Vic Police. 

An autopsy later determined Mary Anne died from stab wounds that pierced her lungs, heart and stomach. She'd been bound and gagged with the same towel that had been draped over her shoulders to prevent bleach from staining her dress.

"The frenzied way in which Mrs Fagan was attacked indicates the person was not thinking sanely at the time," then-homicide squad chief Noel Jubb told The Age days after her murder in 1978.

Forty-six years on, the family of Mary Anne are still hoping for answers on who killed their mother and why.

Anthony Fagan, Mary Anne and Collins' eldest child, said that his mum was a "kind and caring person".

"She was outgoing and had an open, engaging personality and a beautiful smile," he recalled. "The horror and disbelief at what had happened to Mum was indescribable."

He remembered their childhood as perfect, filled with Sunday roast dinners, board games and family picnics. Their parents were loving and doting.

The murder left their family permanently scarred, and the fact that there are more questions and answers following her death doesn't ease the pain. There were items taken from the family home tbhat day, including the knife used to stab Mary Anne and a "red imitation leather handbag", which have never been recovered, police said.

While the case has remained dormant for a long time, in February this year, Victoria Police took a new step forward in trying to find answers about the murder, announcing a $1 million reward for anyone who can offer clues that will help solve the decades-long mystery.

Despite an investigation into what happened, the motive for Mary Anne's killing has never been established. Charges have not been made either. Detectives believe there may still be people in the community who are aware of what happened to Mary Anne and who is responsible for the tragedy.

"We know her family still feel her loss as keenly as they did 46 years ago," Victoria police homicide squad's Det Insp Dean Thomas said in a statement. "Each of her children has had to grow up without their mother and I know they have thought about that almost every day.

"Mary Anne was brutally murdered for no apparent reason in the place she should have felt safest, and with her 17-month-old baby nearby."

A reward of $20,000 was first offered in April 1978, which was increased to $50,000 in June of the same year. Detectives have interviewed more than a dozen people over the years and although there have been no arrests, they are still confident the cold case can be solved.

"Hopefully this public appeal provides the motivation for someone to contact police after all these years," Detective Dean said.

Rebecca, one of Collins and Mary Anne's daughters, said watching their father raise her and her siblings as a single dad was painful. "Watching Dad being a single father, I was very aware even at the age of 12 of his pain. I think we all knew how much he suffered," she explained. 

"I think Dad held a lot of upset and disbelief about how [the investigation] was handled."

Collins died in 2010 and fought right to the end for the reward for information about his wife's murder to be increased.

He also tried to persuade detectives to test forensic samples collected at the scene for DNA. These included pieces of towel, blood swabs, a singlet, and a Winston cigarette butt.

While the Fagan children continue to hold out hope that the killer may one day be identified, they will mourn the loss of Mary Anne for the rest of their lives.

"Mum's loss is something that is permanently in the background of my subconscious and regularly in my everyday thoughts," Anthony said. "We have always held hope that justice would finally be served."

Anyone with information about Fagan’s death can contact Crime Stoppers on 1800 333 000 or submit a confidential report online here.

Feature Image: Vic Police.