Ina-Doris Warrick was excited to return to work as a nurse at a Melbourne hospital months after the sudden death of her husband from bowel cancer.
She was in a secret affair with married anaesthetist Gregor Stewart, supportive of his need to be with his family and happy to steal moments with him when she could.
Ms Warrick was struggling financially with medical bills and was in a dispute with her late husband's family over his will, but she had friends rally around her, including the man accused of ending her life.
Colin Graham was the last known person to see her alive on March 21, 1986, six months after her husband's death.
"We say he caused her death by intentionally stabbing her twice in the back, minutes after returning from the pizza restaurant," prosecutor Robyn Harper told a jury in his murder trial.
A Victorian Supreme Court jury was discharged on Tuesday, unable to reach a verdict.
Graham, who is on bail, will stand trial again at a later date.
They worked together at Box Hill hospital where he was an orderly.
Ms Warrick and her husband were friends with Graham and his wife. The couples went through IVF at the same time.
Ms Warrick even asked Graham to consider being a sperm donor.
Graham told police he had dinner with Ms Warrick the night she died and he had said goodbye to her at her front door.
After the cold case investigation was launched though, three men came forward and said Graham made confessions of sorts to them about her death.
One man said Graham told him a Ringwood nurse he had been seeing died in his arms. Another said Graham told him he committed a murder and not been caught.
The third, a man known as Witness Q, said Graham appeared cold as he recounted how he smothered a woman named Ina-Doris on her couch because she turned him down for sex.
"It was like he was replaying it in his mind and bragging to me about it. It was blood curdling," the man said.
Graham's barrister Malcolm Thomas argued the prosecutors had not proven beyond reasonable doubt that his client killed Ms Warrick.
He claimed the evidence left the door open for another man to have killed her - the man she was having an affair with, Dr Stewart.
They saw each other twice on the day she died. He visited in the morning to help with housework and later left work to have a coffee and to go shopping with her.
Dr Stewart lied to police about when he last saw Ms Warrick. He acted shocked when officers went to his house to tell him neighbours had found her body.
But he had found her body two days prior and told no-one.
"My vision and everything just funnelled down and I lost good concept of what to do," he told Graham's trial.
"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 was asked by Ms Harper if he killed Ms Warrick. He denied it.
Graham also denied it when police interviewed him in 1986.
"How did it come about that you stabbed her?" officers asked.
"I didn't bloody stab her," Graham replied.
