School friends and church acquaintances remember Birnie's family as having been dysfunctional and subject to frequent rumours involving alcoholism, promiscuity and incest.

In the early 1960s, Birnie's parents decided to move the family to another Perth suburb, where he eventually met Catherine Harrison through mutual friends.

One night, Birnie, wearing only stockings over his head, broke into the room of an elderly lady where he was boarding and attempted to rape her.

"[2] In late 1986, at the time of the murders, Birnie was employed at a car wrecker's shop in the Perth suburb of Willagee.

Her father pleaded with her on several occasions to leave David as her involvement with him led to her getting into trouble with police, resulting in her being sent to a youth prison in adolescence.

The sole exception was their final victim, who escaped the day after her abduction and led police back to the Birnie house, thus ending their crime spree.

Twenty-two-year-old Mary Neilson, a psychology student at the University of Western Australia and part-time delicatessen worker, met David at the car wrecker's shop where he worked.

[6] Upon visiting Moorhouse Street on 6 October 1986,[6] Neilson was gagged, chained to a bed, and raped by David while Catherine observed.

Two weeks later, Susannah Candy, a 15-year-old high school student from Nedlands, was abducted while hitchhiking along the Stirling Highway in Claremont.

The Birnies forced her to send letters to her family to assure them that she was all right, then took Candy to Moorhouse Street and subjected her to the same ordeal as Neilson.

Afterward, after an abortive attempt to strangle the girl with the nylon cord, the Birnies forced sleeping pills down her throat.

Once they took effect, David put the cord around her neck and told Catherine to prove her undying love for him by murdering the girl herself.

Females hurt and destroy males.On 1 November, 31-year-old Noelene Patterson ran out of fuel on Canning Highway while on her way home from her job as bar manager at the Nedlands Golf Club.

Patterson was picked up by the Birnies and, similar to the first two victims, was forcibly taken to Moorhouse Street and repeatedly raped by David.

The Birnies originally decided to murder Patterson that same night, but David kept her prisoner in the house for three days amid an apparent emotional attachment to the woman.

The following afternoon, Brown was taken to the Wanneroo pine plantation where, in the seclusion of the forest, David raped her in the couple's car while they waited for darkness.

[12] After David went to work on the day following her capture, Catherine went to the front door to carry out a drug deal and forgot to chain Moir to the bed.

[9] Moir stated the couple had watched the film Rocky on video, and described a drawing she had concealed in the house as proof of her presence.

After being found sane enough to stand trial, Catherine was also sentenced to four terms of life imprisonment[18] by the Supreme Court of Western Australia; under law at the time, both were required to serve twenty years before being eligible for parole.

[5] Various factors led to his suicide; a failure to provide him with his antidepressants had exacerbated his depression, his computer had been confiscated and he was suspected of sexually assaulting another prisoner.

[24] Catherine's case was to be reviewed again in January 2010; however, on 14 March 2009, new Western Australian Attorney-General Christian Porter, following requests from the victims' families, determined she would stay in jail for life.

[29] In 2017, Catherine's youngest son, under the alias Peter, called for her execution, stating that his relation to her has resulted in him being assaulted on multiple occasions.