But on this particular occasion, he planned to make someone disappear.

It was late May in 2014 and the sun had just dipped out of sight when Rogerson and Glen McNamara cracked open a six-pack of James Boag's inside a seaside apartment at Cronulla.

Rogerson was wearing a t-shirt, hat and black tracksuit pants– all of which were covered in gunshot residue.

McNamara's daughter Jessica sat on an ottoman chatting to the pair and noticed that her father appeared "pale" and "twitchy". She had no idea what was hidden in the car park several floors below.

Stuffed inside a silver Ocean & Earth surfboard bag was the body of 20-year-old university student Jamie Gao.

Gao's cousin Justin knew something was not right and went with some friends to the last place Gao had been seen, near a storage facility at Padstow in Sydney's south-west. He walked around for hours calling out his cousin's name but no sound came back.

Two years after screaming out his cousin's name, Justin and the Gao family finally got what they had been hoping for on Wednesday. After a four-month trial, a jury found the disgraced former detectives – Rogerson and McNamara – guilty of Gao's murder. The five women and seven men of the jury also found the pair guilty of supplying a commercial quantity of a prohibited drug.

McNamara, wearing a navy blue suit and a striped tie, did not react as the jury forewoman read out the verdict.

Rogerson, cloaked in an oversized camel blazer, showed no emotion and put his left hand on a piece of paper he appeared to be reading.

Outside the court the investigating police paid their respects to Gao, a young university student and aspiring drug dealer.

"I feel for the family, for Jamie Gao's family, I feel for him; regardless of what was said about young Jamie, he's still a human being,"

Detective Chief Inspector Russell Oxford said. "He could have been any one of our sons or daughters or grandchildren.

"I think that's probably what's lost in today, is [that] Jamie Gao has been executed."

Old cop buddies

Rogerson and McNamara were once two close friends who worked together, drank together, went to boxing matches, book launches – they even shared a bunk bed in the same cell for 52 nights.

But the story they concocted to get off murder charges was certainly not the same one presented to the jury during their 18-week trial in the NSW Supreme Court this year.

The pair had well and truly turned on each other.

Some aspects of their story remained the same – the parts where they were caught on CCTV footage.

But where their versions separate is inside unit 803 at Rent a Space, Padstow.

At 1.46pm on May 20, security footage captures Gao getting out of a white Ford station wagon and slipping into an unlit storage shed.

A little more than three minutes later, Rogerson is seen hobbling towards the unit. He opens the roller door and closes it behind him after he walks in.

If you believe Rogerson, he opened the door to a "nightmare". "Well [McNamara] was as white as a ghost, he was shaking uncontrollably and sweating like a pig," he told the jury, gripping the witness stand with both hands.

"Then I looked down and I saw an Asian man lying on the floor with his head to my right ... and he was dead."

On Rogerson's version, McNamara told him there had been a struggle, and that Gao had shot himself twice in the chest.

"I said to him, 'Glen the only thing we'll be doing here is calling the cops'," Rogerson's version goes.

But McNamara explained that, unless they left the area quickly, the two of them would be killed by Chinese Triad members that Gao associated with.

McNamara paints a very different picture.

He said he was in the shed for three minutes with Gao by himself but could not explain why or what they spoke about. The next thing he remembers is Rogerson opening the shed door and demanding Gao hand over the "gear".

Gao pulled out a combat-style knife and simultaneously Rogerson produced a gun from the right pocket of his pants. "[Rogerson] held aim and shot him again. Gao stopped moving, there was no noise ... he just killed him."

He said Rogerson then aimed the gun at his head and threatened to kill him and his daughters if he did not help dispose of the body.

The gun has never been found.

Storage shed 803

But why were two old, former detectives and a young university student inside a storage shed in the first place?

During his closing address, Crown Prosecutor Christopher Maxwell, QC, outlined how the three men were there to do a drug deal. But what Gao did not realise was that Rogerson and McNamara's plan was to steal the 2.78kilograms of ice he had brought them. The drugs were later found in two brown pillowslips in a car parked in McNamara's garage.

"[Jamie Gao] went into that storage shed with the expectation that what was to happen in there would shortly make him very rich. Instead he was shot and killed, dragged into the back of a white station wagon and his body dumped out to sea," Mr Maxwell said.

It did not matter who pulled the trigger because the pair were part of a joint criminal enterprise to murder Gao and make him "disappear", Mr Maxwell said.

And it was a plan that involved much preparation.

The first steps were taken in early 2014 by McNamara.

McNamara was working on a drugs matter in his capacity as a private investigator for one of Gao's friends who had been charged by the police.

Gao acted as a Cantonese interpreter between his friend Lok Lam and McNamara.

From here the pair forged a close relationship, and would meet some 27 times and send hundreds of texts in the lead-up to the fateful day in the storage shed.

McNamara claimed Gao was his informant for the next true crime book he was writing on the triads and drug dealing in Sydney.

During this time, Rogerson was in charge of finding the perfect place to carry out the deal – and kill.

Police allege Rogerson got the keys to unit 803 – where Gao was killed – from an old friend called Michael McGuire.

In further preparation, the Crown argued the pair would buy a white Ford station wagon with the number plates BV6 7PX on April 27 from Outback Used Cars at Lethbridge Park. Both denied having anything to do with the car's acquisition but police found a receipt for the car in McNamara's Cronulla apartment with Rogerson's right index fingerprint on it.

The day before the killing, Rogerson drove to unit 803 and removed a number of chairs from the storage shed and placed them in the back of his silver station wagon.

McNamara was also busy on May 19. He is seen taking his Quintrex boat out of Hunter Self Storage at Taren Point and tow it away with his blue Ford Falcon. This is the boat that would later be used to dump Gao's body at sea.

The day of the killing

On the morning of the killing, McNamara went to Cronulla Mall and used a public telephone to call Gao at 11.37am.

One minute later Gao wrote back: "Hey it was great having a drink with you last night, but I'm not in the mood to study today, I was wondering if you wanted to grab lunch this afternoon."

At 1.17pm Rogerson and McNamara drove to unit 803.

Rogerson told the jury he agreed to be a "second set of eyes" for McNamara, who told him he was meeting a valuable informant for his book but was worried about being followed by Chinese triads.

The only thing Rogerson says he planned to do that day was mow his lawns and sweep the gutters.

McNamara claimed they were at the shed to fix a stiff door – WD40 would have done the trick, he thought.

They then drove the untraceable car – BV7 6PX – and Rogerson's silver Ford station wagon to nearby Arab Road – all captured on security cameras from a business called Mick's Meat in Padstow.

Here Gao pulls up in his Nissan Silvia with two other men. He gets out and gets into the rear passenger door of the white station wagon holding a white bag.

After a short drive, McNamara arrives at Rent a Space and Gao is escorted into unit 803 at 1.46pm.

Half an hour later Rogerson and McNamara are seen dragging Gao's body out, stuffed inside the silver surfboard bag.

They load it into the back of the white station wagon, pack a couple of chairs on top and drive to McNamara's apartment at Cronulla.

But they realise there is a problem when they drive down to the basement – neither of them are strong enough to lift Gao's body into McNamara's boat which is parked downstairs and ready.

So they went to Kennards Hire at Taren Point where they are again captured on security footage, hiring a two-tonne chain block.

Later they hoist Gao's body into the boat, they grab a six pack of beer and head upstairs.

Their dirty work is done for the day.

The following morning Rogerson and McNamara arm themselves with fishing rods as they leave McNamara's apartment.

"It is the Crown case that what happened in that boat that day had nothing to do with fishing but everything to do with getting rid of the deceased," Mr Maxwell said.

But making Gao disappear did not go to plan.

Six days later fishermen would spot Gao's body – wrapped in blue tarpaulin – and floating 2.5 kilometres off Shelly Beach at Cronulla.