Terrifying masked criminal Mr Cruel has never been found despite his heinous crimes

Warning: This article contains discussion of child abuse which some readers may find distressing

It's been more than three decades since the heinous attacks of a masked criminal, known as Mr Cruel, rocked the suburbs of Melbourne, Australia, and yet his identity has still never been revealed.

In August 1987, the serial child rapist began his horrifying crime spree when he broke into the family home of an 11-year-old girl, tied up her parents and locked them in a closest, tied her seven-year-old brother to a bed, before going on to sexually assault the girl.

The masked criminal then cut the family's phone lines and fled, leaving behind not a single trace of forensic evidence.

After reporting the attack to police, the young girl told officers she heard the man making a threatening phone call, telling the recipient of the call to 'move their children' or they would 'be next' in what went on to become a string of vile attacks.

But despite wide scale investigations, police found no evidence of this phone call and later claimed it was a red herring to throw them off track.

Victoria Police

The second attack

A year and a half later, just after Christmas 1988, the masked attacker struck again just miles away from where the first assault had taken place.

Mr Cruel, as he later became known, entered the home of the Wills family brandishing a knife and wearing blue overalls and a dark ski mask. As he had done previously, he gagged the parents and tied them up, before assuring them he was only there for money.

However, he went on to cut the phone lines and head towards the bedroom of the Wills' four daughters, before addressing 10-year-old Sharon Wills by name.

After waking her up, he gagged and blindfolded the child, before fleeing the home with her and several items of her clothing in the early hours of the morning.

Eventually, Sharon's dad John managed to free himself and rush to a neighbor's home to alert police. Around 18 hours later, Sharon was found abandoned on a street corner, dressed in garbage bags, yet immaculately clean.

While maintaining her blindfold, the attacker had made sure to bath his victim, clip her finger and toenails and brush and floss her teeth, to avoid any forensic evidence remaining on her body.

After police surmised that the attacks were committed by the same man, families in the Melbourne area were left petrified that he would strike again - and they were right.

Victoria Police

The third attack

A year and a half later, this time in the suburb of Canterbury, Victoria, Mr Cruel entered the home of an English family who were renting a house in an affluent area home to many politicians and public officials.

On the night of the attack, parents Brian and Rosemary Lynas had left their daughters, Fiona, 15, and Nicola, 13, home alone while they attended a party.

The man gagged and tied up the older sister, before leaving her with a ransom note and informing her that her father would need to pay $25,000 to get his daughter back, before leaving with a blindfolded Nicola in the family's rental car and swapping vehicles just down the road.

Around 20 minutes, the parents returned home to discover the horror that had unfolded. Days later, however, Nicola was dropped off near her home, fully dressed and still blindfolded. She managed to make her way to a nearby home and call for her parents at around 2am.

Despite their confidence all three attacks were committed by the same man, police were unable to track the criminal down.

Nicola did manage to provide some useful information about Mr Cruel, including the fact that he was around five-foot-eight tall and had reddish brown hair, and she also shared disturbing details about the horror she had faced while in his captivity.

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The fourth and most deadly attack

The following year, in April 1991, the now-serial attacker would go onto his most violent spree yet, when he broke into the home of the Chan family.

Karmein Chan, 13, was left to care for her two younger siblings while her parents John and Phyllis were out for the evening, when Mr Cruel struck for a fourth time.

After entering the home, he told the girls he was only after their money, before locking the two younger sisters in the closet and escaping with Karmein.

However, the younger sisters managed to break free minutes later and quickly alerted their parents, who called the police.

Authorities immediately knew this to be the work of Mr Cruel, and launched one of the biggest search operations in Australia's history, but the Chan family would never be reunited with their eldest daughter.

Around a year later, a dog walker discovered a decomposed skeleton which was later confirmed to belong to Karmein. An autopsy revealed the teen had been shot in the head three times, prompting the theory she had learned too much about her attacker to be let go.

Police continued to search for clues to catch and unmask the attacker until the case was eventually shelved in 1994.

Mr Cruel's identity remains a mystery to this day.