An anaesthesiologist who was having an affair with murdered Melbourne nurse Ina-Doris Warrick has denied killing her.
Gregor Stewart was giving evidence in the trial of Colin Graham, who is accused of her 1986 murder and has pleaded not guilty.
Graham, a hospital orderly, is alleged to have killed Ms Warrick, 25, in her Ringwood home after taking her out for dinner.
But his lawyers say prosecutors haven't ruled out Dr Stewart as the killer.
Dr Stewart told Victoria's Supreme Court on Wednesday that despite him being married he and Ms Warrick were "two bodies with one soul".
As well as their "intimate friendship" he said they had a trust that resulted in him being the anaesthetist when Ms Warrick had a hysterectomy four months before her death.
He also admitted prescribing her opiates and on one occasion injecting her himself, but denied any knowledge of suggestions Ms Warrick had been let go from a nursing job because of an opiate addiction.
Asked about the ethics, he said he thought it was "reasonable behaviour but maybe not totally correct".
He also denied having a key to let himself into Ms Warrick's home so he could inject her with medication after she had taken a sleeping tablet.
Dr Stewart says he last saw Ms Warrick alive twice on the day she is believed to have been killed - Friday March 21, 1986.
He helped with morning house work and met her at 5pm for coffee and shopping in Box Hill. He told the court he was home with his wife and children that night.
Graham's barrister Malcolm Thomas grilled Dr Stewart on his decision not to drive 20 minutes to see Ms Warrick before she worked that night, but instead drove a 90-minute return trip the following morning on a tight time frame during his son's cricket match.
The doctor said he said hello to a neighbour but left when Ms Warrick didn't answer the door, believing she was asleep after her night shift.
He also didn't try to call her over the weekend, despite Mr Thomas suggesting they spoke frequently on the phone.
Dr Stewart discovered Ms Warrick's body in her home on the Sunday night, but admitted in court he deliberately lied in two police interviews and a formal statement, despite knowing he was a suspect.
He said he saw her on her bed and knew she was dead.
"My vision and everything just funnelled down and I lost good concept of what to do," he said.
"I left the bedroom and went out into the hallway. I can remember and still feel just an incredible distress feeling in my body, in my mind."
Dr Stewart drove away, but returned moments later and briefly went back inside before driving home.
He went to work in surgery on Monday and Tuesday.
Dr Stewart admitted the affair to his wife on the Wednesday but continued to lie to police about finding Ms Warrick's body until Friday.
"Dr Stewart did you kill Ina-Doris Warrick," prosecutor Robyn Harper asked him.
"No I did not," he replied.
