Born in 1949 in Brunswick, Flannery left school at the age of fourteen.

He received his first criminal conviction later that year.

At 17, he was convicted of housebreaking, car theft, assault against police, carrying firearms and rape.

He was sentenced to seven years imprisonment.

In 1974, Flannery and two other men were alleged to have committed an armed robbery on a David Jones store in Perth.

They were arrested in Sydney by former Detective Sergeant Roger Rogerson.

It has been alleged that Flannery paid a bribe to Rogerson to escape conviction.

Flannery was extradited to Perth but acquitted at trial.

However, he was jailed on an outstanding Victorian warrant for rape.

On his release from prison, he became a bouncer at Mickey's Disco, a massage parlour in St Kilda.

But he was quickly bored by the work and moved into contract killing.

On May 11, 1979, Sydney brothel owner, Raymond Francis "Lizard" Locksley was murdered at Menai.

Flannery was later arrested.

According to police, another of Flannery's first jobs was the murder of barrister Roger Anthony Wilson.

In August, 1980, Flannery, Mark Alfred Clarkson and John Henry Williams were arrested and charged with Wilson's murder.

Wilson's body was never found but police alleged that the trio had forced him off the road, abducted him and took him to Pakenham, where Flannery took him into the to the bush to shoot him.

Flannery is said to have missed and Wilson, bleeding profusely from a head wound, tried to escape.

Flannery is then alleged to have gone "mad" and emptied his gun into Wilson's head and back. 

In October, 1981, Flannery was unexpectedly acquitted but as he left the court, detectives from New South Wales Police immediately arrested him for the murder of Raymond Locksley.

In 1982 a jury failed to reach a verdict and a retrial was adjourned until April 18, 1984.

Flannery was subsequently acquitted.

After his acquittal, Flannery bought a house in Arncliffe and brought his wife, Kathleen, and children up from Melbourne.

Flannery went to work as a bodyguard for Sydney crime figure George Freeman.

In late 1984, he became embroiled in the Sydney "gang wars" and sided with Neddy Smith (left).

Smith claims that Flannery became paranoid and "was running around shooting at anyone he thought had anything to do with underworld figures Barry McCann or Tom Domican."

He claims that police attempted to negotiate an end to the gang wars but that Flannery refused to stop the killings.

At one meeting, according to Smith, Flannery told a high ranking police officer, "You're not a protected species, you know – you're not a fucking koala bear!"

On June 6, 1984, Flannery is alleged to have been the gunman in the attempted execution of Sydney Drug Squad detective, Mick Drury.

Drury had been the undercover agent involved in a police drug operation which resulted in charges being laid against Flannery's friend, Alan Williams.

Williams later testified that Flannery had attempted to bribe Drury through Roger Rogerson in order to get the charges against Williams dismissed.

When Drury rejected repeated attempts at bribery, Williams claims, he agreed to pay Flannery and Rogerson $50,000 each to murder Drury.

On what he thought was his deathbed, Drury told detectives he believed he was shot because of "the Melbourne job."

Melbourne gangster Alphonse Gangitano later became known as the person who killed prostitute, Deborah Boundy.

She had been about to give evidence against Flannery.

As Flannery and his wife walked towards their house on January 27, 1985, the house was sprayed with 30 shots from an Armalite rifle.

No one was seriously injured, though Flannery was shot through the hand as he pushed his wife's head down and he suffered some other minor abrasions.

Flannery blamed Tom Domican who was later charged and convicted of attempted murder, but the conviction was over-turned on appeal.

Rogerson was seen in the area in the days after the shooting and was interviewed by police.

He claimed he was just curious to see what kind of damage such a gun could do and was released without charge.

Drury was also interviewed, but was not considered a serious suspect.

Williams, who was a friend of big time speed dealer John William Higgs.

It has been alleged that Higgs was involved in the killing of two people over the Drury deal.

On April 23, 1985, it is alleged that Flannery's employer, George Freeman, sent him to murder his friend, Tony Eustace.

Eustace was found by two schoolchildren who were returning home from sports training at about 7 pm.

He had been shot six times in the back and was lying beside his gold Mercedes, bleeding profusely.

He was rushed to hospital.

Police attempted to speak to him, asking who had shot him, but Eustace told them to "fuck off" and died a short time later.

After the attempt on his life, Flannery leased an apartment at the Connaught building

This meant that Flannery's new home was almost adjacent to the CIB headquarters at that time.

On May 9, 1985, he received a phone call from Freeman, instructing Flannery to meet him.

Flannery went to the garage but found his new car would not start.

He rushed back to the apartment to call Freeman, who told him to catch a taxi.

Flannery then exited the building and was never seen again.

Neddy Smith claims that while waiting for a taxi, two police detectives Flannery was friendly with stopped and offered him a lift.

Allegedly, Flannery got into the backseat and at the next set of traffic lights, another two police officers got into the car on either side of him and before he could react, the officer in the front seat turned around and shot Flannery.

Flannery's body has never been found and no one has been charged with his murder.

On June 6, 1997, New South Wales State Coroner Greg Glass handed down the finding that Flannery was murdered most probably on or about May 9, 1985.

Glass also found that the key to solving his murder lies with former detective Roger Rogerson.

On February 22, 2004, Rogerson told the Sunday program, "Flannery was a complete pest."

"The guys up here in Sydney tried to settle him down. They tried to look after him as best they could, but he was, I believe, out of control. Maybe it was the Melbourne instinct coming out of him. He didn't want to do as he was told, he was out of control, and having overstepped that line, well, I suppose they said he had to go but I can assure you I had nothing to do with it."

Flannery is survived by his wife, Kathleen, and two children.

Police have alleged he was responsible for up to a dozen murders.