Matthew Leveson died from taking the drug GHB, according to his boyfriend Michael Atkins who found his 20-year-old lover's body the next day, it was revealed in a bombshell announcement yesterday.
A "bottle of drugs" containing the substance GHB was found in the kitchen near the body of Leveson, who died after a night arguing with his boyfriend Atkins, the inquest into Leveson's death heard.
Detective Chief Inspector Gary Jubelin said Atkins' account of Leveson's death was that after arguing at ARQ nightclub in 2007, the pair drove home and slept in separate areas.
Atkins "fell asleep in the lounge" and Leveson went to sleep in a bedroom and Atkins found his body dead in their flat the next morning.
Atkins told police he found the "bottle of drugs" in the kitchen of their flat and he "assumed that might have caused Matthew's death".
Jubelin said Atkins spent some time with Matthew's body before deciding to bury it in bushland.
Leveson's father asked questions that threw doubt on Atkins' account of what had happened to Matthew.
Mark Leveson asked Leveson whether Atkins could have been "panicked and still drug affected" when he discovered Matthew's dead body.
"Yet he drove home six hours earlier?," Mark Leveson said.
"And he said (in Atkins' statement to police) 'I thought I was going to be named and shamed'."
Jubelin said he didn't believe Atkins would have trouble breaking driving laws and he was "morally bankrupt ... basically has no morals".
Asked whether Atkins was still considered the only person of interest in Matthew Leveson's death, Jubelin said he was "comfortable with that".
Asked by the Coroner whether the clothing Atkins had worn on the night Matthew died had never been found, Jubelin agreed.
Evidence was given of fish-shaped containers of GHB and the barrel of a syringe for apportioning the drug for sale.
In questions to Jubelin, Coroner Truscott asked whether Atkins' account that he left ARQ nightclub to take a heavily drug-affected Matthew home was inconsistent with CCTV footage.
Truscott said the 55 minutes after Atkins left the club were unaccounted for by him, and that the inquest had heard he went to get more drugs to sell rather than drive Matthew home.
Jubelin agreed, and also agreed that a friend of Atkins, Jack Smith, had been down a side alley with two others in a manner "consistent with drug dealing".
Mark Leveson asked Jubelin whether another person could have been involved in the disposal of Matthew's body.
Jubelin said he believed Atkins "acted alone".
Outside court, a tearful Faye Leveson said she didn't believe his lover Michael Atkins' story that the 20-year-old died from a drug overdose.
After a day in which it was said that Atkins, 53, had lied and changed his story about how Matt Leveson died in 2007, Faye and Mark Leveson described Atkins as a "proven liar".
Weeping on the steps of Glebe Coroner's Court, Leveson said of her son, "I don't believe he OD'd.
"Can you believe anything that (Atkins) says?
"In that case, he was in a room - with our dead son - on the internet getting tickets to the Sleaze Ball.
"Is that the action of someone who loves someone?"
Leveson said: "What I'd like to happen is to at least make him face court."
NSW Deputy State Coroner Elaine Truscott will decide tomorrow whether Atkins should return to the witness box to give evidence in the inquest.
Counsel Assisting the inquest Tim Game SC questioned whether it would not be a "probably highly fruitless task" given that he could not rely on Atkins to tell the truth and that "the question of his credibility is so compromised".
Leveson said outside the court that they had fewer rights than Atkins.
"He's the one with all the rights. We have had to sit through court hearings hoping to find Matt.
"Why didn't he say that 10 years ago? Why didn't he ring Triple-0?"
Leveson's father said he hoped police would take time to properly test forensic evidence in their son's case.
Atkins told police the reason he decided to cover up his boyfriend's death was fear about his reputation and the fact he had only recently come out as a homosexual.
"He (Atkins) had concerns about his reputation," Jubelin said.
"He was the older partner of a young male, had only recently come out as a homosexual.
"He was responsible for looking out for him (Leveson).
"His (Atkins') mother didn't know he was homosexual."
Later on that Sunday, Atkins formed the plan to dispose of the body and went to Bunnings to buy a mattock and duct tape.
He wrapped Leveson's body "in a blanket or sheet" and pushed Leveson's car out of the car space after removing the boom box from the boot to make room for Leveson's body.
Atkins waited until it became dark and drove to Waterfall in the Royal National Park at around midnight.
He carried Leveson's body from the car to a spot in the bush and began digging a hole.
Asked by Counsel Assisting the inquest Tim Game SC whether the account was inconsistent with Atkins' previous stories, Insp. Jubelin said "yes".
Jubelin agreed with Mr Game that the case may have been dealt with differently if it was being handled currently.
He agreed that evidence, such as the Bunnings purchases, withheld from Atkins' murder trial, might have been included if the case had been handled differently.
Asked by Coroner Elaine Truscott when exactly the "bottle of drugs" that had been seen "later" by Atkins in the couple's kitchen, Jubelin said he wasn't sure of when Atkins meant.
The dramatic scenes of finding Leveson's body also emerged in the Sydney court.
On May 31 this year, on the third attempt to locate the missing 20-year-old, an excavator found Leveson's skull.
Jubelin said using a new shallow digging method, the police excavator unearthed the skeleton "on the second or third scrape" of the earth.
His skull and some bones were found near a cabbage palm.
"You could see a portion of his skull," he said.
A post mortem analysis of Leveson's bones that found damage to the bones determined it could have been inflicted either before or after death.
Jubelin agreed that excavation of the area in which Leveson's remains were believed to be could have caused the bone damage.
He said the "pure logistics" of the search made it difficult and the almost 10 years since Leveson's death meant cadaver dogs and ground penetrating radar might not be useful.
The inquest also heard Atkins buried Leveson's body in a two metre by one metre grave that was just 800mm deep.
Police also gave Atkins a 70kg mannequin to put in and remove from a vehicle in the Royal National Park south of Sydney in an attempt to find Leveson's remains.
And Matthew Leveson's family agreed to lending police their son's car, which Atkins used over three days to refresh his memory about where he buried Leveson in 2007.
Giving evidence at Leveson's inquest in Sydney, Jubelin said Atkins had given police graphic details of the hole he had dug.
Police took him to areas in bushland during the day and at night in efforts to help him remember where he had buried Leveson.
Atkins told police the burial site was 4km from Waterfall Railway Station, south of Sydney, on a slope and near a hairpin bend.
Inspector Jubelin said police had driven with Atkins late last year after he drew a diagram of where he had buried his 20-year-old lover.
"We were directed by Atkins in a car ... to Waterfall (railway station) and to McKell Avenue, the road where the body was found," Insp Jubelin said.
"Atkins ... was confident it was that road. He had a look around.
"We continued along the road and there was another car park ... a gravel clearing that leads on to a walking track with a hairpin bend.
"When we got out Atkins seemed to be more confident."
Jubelin said a police excavator used in two attempts to find Matthew's body had been employed a third time, in May this year, using a shallow "scraping".
This replaced earlier deeper digging after Atkins indicated the size of the hole he buried Matthew in.
A statement made by Atkins outlining what happened before Matthew's death and describing where he had buried his lover's body was tendered to the inquest.
Leveson's remains were found in bushland two months ago, in the Royal National Park south of Sydney.
His remains were located after the inquest was halted last year and Atkins was granted immunity to provide details of where Leveson's body could be found.
Atkins drew a diagram for police of where he buried Leveson's body.
He said the body was located "3-4km from Waterfall railway line" near "a bend in the road swinging towards the right and on the left-hand side a small car park ... and a grave 15 to 20 metres away".
However Counsel Assisting the inquest, Tim Game SC told Deputy State Coroner Elaine Truscott that she should not rely on Atkins' credibility regarding the cause of Leveson's death.
Game said that "in terms of credibility of the circumstances ... we were not putting that forward to you, that you should make findings based on that".
Atkins' legal counsel is arguing against his being compelled to return to the witness box to give evidence.
Leveson's parents Mark and Faye and friends appeared at the inquest at Glebe Coroner's Court in Sydney wearing purple in his memory.
Jason Leveson, Matthew's brother, refused to take his cap off in court after Ms Truscott requested he did, and wore it during the hearing.
The Levesons never gave up on finding their son's body, spending every day at the site while the excavator dug for remains last November, in January and on the final successful mission two months ago.
Leveson was last seen leaving ARQ nightclub in Sydney's inner city suburb of Darlinghurst with his then-boyfriend, Mr Atkins, in 2007.
Atkins, who was acquitted of Leveson's murder by a trial jury in 2009, was caught on CCTV in Bunnings buying duct tape and a mattock the day after Leveson vanished.
The inquest had previously heard Atkins suggest that Leveson may have gone overseas to Thailand.
After he struck a deal with the NSW Attorney-General for immunity from perjury and contempt of court, Atkins led police to the burial site in the Royal National Park.
Legal experts say it is unlikely fresh charges would be laid against Atkins because of the immunity arrangement.
Following confirmation their son's remains had been found, Mark and Faye Leveson thanked loved ones on Facebook who had supported them in the search for the 20-year-old.
"It has now been CONFIRMED by DNA testing that the remains found WERE OF OUR BELOVED MATTY," a post on the Justice for Matthew Leveson page published in June.
Before an inquest hearing in February this year, Mark Leveson told news.com.au that the family were hoping to learn about all the circumstances of "Matty's death".
"I want to find out how he died, and where his body is," Leveson said.
Now aged 54, Mr Atkins was a sexually active gay man in 2007 when his much younger boyfriend Leveson disappeared.
According to evidence given at the trial and at Mr Leveson's inquest, Atkins was known as the older guy who liked threesomes and lured young men with the promise of drugs.
Evidence was given at an inquest hearing in 2015 that Leveson and Atkins were small-time suppliers of GHB and ecstasy.
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