One of two detectives behind the cold-blooded execution of Sydney drug dealer Jamie Gao helped dispose of the body because he feared for his own life, a court has heard.

The NSW Court of Appeal today heard Glen McNamara was terrified of Roger Rogerson, who he said told him he had committed several murders months before the deadly shooting of Jamie Gao.

The former police officers are appealing their life sentences for the murder of the 20-year-old inside a storage facility at Padstow in Sydney’s south-west in May 2014.

They stole almost three kilograms of the drug ‘ice’ from him — with an estimated street value of $19 million — before dumping his body in waters off Cronulla.

In February 2014, Rogerson told McNamara he had killed several people, including heroin dealer Warren Lanfranchi, who was shot dead in 1981, the court heard.

That evidence was not provided to the jury when both men were found guilty of killing Gao after a 10-day trial in 2016.

Barrister Gabriel Wendler SC, who appeared for McNamara, argued it amounted to a “miscarriage of justice”.

Jamie Gao’s body was dumped in waters off Cronulla. Photo: Facebook

“At all times, he had on his mind the capacity of Mr Rogerson to manipulate him and do him harm even in circumstances when they were in custody together,” he said.

The court heard Rogerson threatened to kill McNamara’s children if he didn’t help him get rid of Gao’s body — something he believed given his history.

“He was nevertheless acting under the circumstances he found himself in,” Mr Wendler said.

Rogerson and McNamara have always blamed each other for firing the two fatal shots that killed Gao.

Years later, it remains unclear who pulled the trigger, and the gun itself has never been found.

Barrister John Stratton SC appeared for Rogerson and said it was inconceivable his client planned to murder Gao because of his actions before and after the shooting.

“He brought his own car to the crime scene — it would not make sense for him to do it in his own car if it was planned to either rob or kill the deceased,” he said.

Justice Robert Hulme said he found the theory interesting.

“It is my experience that not each premeditated crime involves skilfully and intelligently thought-through plans,” he said.

“Sometimes, people of reasonable intelligence do some pretty stupid things.”

The Crown argued the court should dismiss all appeals, given the overwhelming evidence that found the men guilty four years ago.

–ABC