"Then I looked down and I saw an Asian man lying on the floor with his head to my right ... and he was dead." Roger Rogerson at the time of his arrest in May 2014. Credit:Nick Moir Wearing a black hearing device and an oversized tanned blazer, Mr Rogerson was giving evidence for the first time at his NSW Supreme Court murder trial on Friday. The 75-year-old and Mr McNamara are both accused of killing university student Jamie Gao, 20, inside a south-western Sydney storage shed in May, 2014. But the former detectives are blaming the murder on each other.

Mr Rogerson told a jury that he had never heard of Mr Gao until after seeing him dead on the floor of unit 803 at Rent a Space, Padstow. Former detective and true-crime author Glen McNamara. Credit:James Alcock In his account he walked into the dimly lit shed and his friend Mr McNamara then explained what had happened. "Glen McNamara said, 'He pulled a gun on me, he tried to kill me'." Mr Rogerson replied, "What the f--- happened?"

In his account, Mr McNamara allegedly claimed Mr Gao had tried shoot to him. "[Mr McNamara] said 'I knew he was going to shoot me' and he said 'I made a grab for his hands ... it was a real struggle.' "[Mr McNamara] said, 'I was able to grab hold of his hands and I was lucky enough to twist the gun around'." Mr McNamara then allegedly said that the deceased had "shot himself in the chest". Leaning forward at times, Mr Rogerson told the jury he believed Mr McNamara when he said that if the pair did not leave soon, they would be killed by Chinese triads with whom Mr Gao associated.

Mr Rogerson said he was adamant the police should be called. "I said to him, 'Glen, I think the only thing we'll be doing here is calling the cops,'" he said. But Mr McNamara was worried the both of them would be killed unless they left the area quickly. "McNamara said to me, 'If he's not back there soon this place will be swarming with Chinese assassins. We're gonna be killed if we don't get out of here as quick as we can." Mr Rogerson was allegedly told "these lunatics will shoot the police" and "this place will become a bloodbath".

"I said 'Well thanks very much Glen, I'm a bit old for all this'." At this point Mr McNamara was allegedly hyperventilating. "I said to him 'Glen, look, pull yourself together, calm down, sit down'." Barrister George Thomas then asked, "Did you believe what he was telling you?" To which Mr Rogerson replied, "I had no reason not to believe everything he said."

"Did you know anything of any plan to kill Jamie Gao?" Mr Thomas asked. "One hundred per cent not," Mr Rogerson replied. Earlier on Friday Mr Rogerson had explained to the jury how he and Mr McNamara had a "strong" relationship and that they had known each other for about five years. Two days before Mr Gao's death, Mr McNamara had come to visit Mr Rogerson on the afternoon of May 18. Mr McNamara explained how he had an informant who had been helping him research his next true crime book on Asian gangs in Sydney.

He allegedly asked Mr Rogerson if he could use a mutual friend's storage unit to have a meeting with a "very, very valuable informant". Mr Rogerson said he did not think it would be a problem. On the day of Mr Gao's death Mr Rogerson said he was at his Padstow home, sweeping the gutters outside when Mr McNamara pulled up in a white Ford station wagon. He said Mr McNamara was about to go meet his informant and asked whether Mr Rogerson could come along to be a "second set of eyes" in case there were Chinese triads following. "Why did you involve yourself?" Mr Thomas asked.

"I had no reason to suspect anything ... When he asked me if I would be his second set of eyes I could see no reason not to help him or be of assistance to him," he said. During his evidence-in-chief Mr McNamara said it was Mr Rogerson who shot Mr Gao dead inside the Rent a Space storage shed. "Rogerson just shot him," Mr McNamara said.