On November 10, 1986, a seventeen-year-old girl ran into a vacuum cleaner shop in Willagee, a suburb of Perth, and told the owner she had been raped. Kate Moir had accepted a ride the night before from a couple who held a knife to her throat, made her phone her mother to say she had drunk too much and was staying with a friend, and took her to their house at 3 Moorhouse Street. When she asked whether they meant to kill or rape her, she was told, "We'll only rape you if you're good." That morning the man went to work, and the woman, going to the front door to do a drug deal, forgot to chain her to the bed. Moir broke the lock on a window and climbed out, hitting her head on the concrete, knocked on neighbors' doors, jumped a gate and was attacked by the couple's dog before she reached the shop.
Some of the officers doubted her at first, but Constable Laura Hancock, twenty-two, believed her because of the detail: the address and phone number, David's name, which she had read on a medicine bottle, the film Rocky, which the couple had watched on video, and a drawing she had hidden in the house as proof she had been there. The police found the drawing, and Rocky in the video recorder. David and Catherine Birnie gave conflicting stories; she denied ever meeting Moir, and he said the girl had come willingly for sex. Detective Sergeant Vince Katich persuaded David to confess and to show where the others were buried.
David John Birnie was born on February 16, 1951, the eldest of five children, and grew up in Wattle Grove, in a family schoolmates and churchgoers remembered as dysfunctional and rumored to be riven by alcoholism, promiscuity and incest; the parents did not cook meals for their children. He met Catherine Harrison through friends when she was twelve. At fifteen he left school to be an apprentice jockey at Ascot Racecourse, where he abused the horses, exposed himself, and one night, wearing only stockings over his head, broke into the room of the elderly woman he boarded with and tried to rape her. He was in and out of prison as a young man, married in his early twenties and had a daughter. Catherine, whose mother had died in childbirth when she was two, went to a youth prison through her involvement with him, then worked as a housekeeper for the McLaughlin family, married Donald McLaughlin on her twenty-first birthday and had seven children. In 1985 she left them and moved in with David, and took his surname by deed poll. In 1986 he worked at a car wrecker's in Willagee.
Mary Neilson, twenty-two, a psychology student at the University of Western Australia, came to Moorhouse Street on October 6, 1986, to buy cheap tires David had offered her. She was gagged, chained to a bed and raped while Catherine watched, then taken to Gleneagle, near Albany Highway in Bedfordale, raped again, strangled with a nylon cord and stabbed, and buried in a shallow grave. About two weeks later they picked up Susannah Candy, fifteen, a high school student from Nedlands, hitchhiking on Stirling Highway in Claremont, and made her write to her family that she was all right. After a failed attempt to strangle her they forced sleeping pills down her throat, and David told Catherine to prove her love by killing the girl herself. She did. Asked later why, she said she wanted to see how strong she was within herself, and that she did not feel a thing.
On November 1, Noelene Patterson, thirty-one, a bar manager at the Nedlands Golf Club, ran out of fuel on Canning Highway and was picked up. David kept her for three days, apparently attached to her, until Catherine, jealous, told him to kill her or she would; he forced sleeping pills on her and strangled her in her sleep, and she was buried at Gleneagle apart from the others. On November 5 they took Denise Brown, twenty-one, from a bus stop on Stirling Highway. The next afternoon, in the Wanneroo pine plantation, David raped her in the car, raped her again, stabbed her in the neck and laid her in a shallow grave; when she sat up, he struck her twice in the head with an ax and buried her. The Birnies have also been suspected in the 1986 disappearances of Cheryl Renwick and Barbara Western.
David Birnie pleaded guilty to four counts of murder and one each of abduction and rape and was sentenced to four terms of life imprisonment; Catherine, found fit to stand trial, received the same, and under the law then both had to serve twenty years before parole. He was held in solitary confinement at Fremantle Prison, in converted death row cells, until it closed in 1991. The couple exchanged more than 2,600 letters and were allowed no other contact. He was found dead in his cell at Casuarina Prison at 4:30 a.m. on October 7, 2005, aged fifty-four; an inquest found he had hanged himself from an air vent with a length of cord, his depression worsened by missed antidepressants, the confiscation of his computer and suspicion that he had sexually assaulted another prisoner.