David John Birnie was born in Perth on February 16, 1951, into a chaotic and violent household, and met Catherine Harrison when both were teenagers. They committed burglaries together as adolescents, separated for years while she married and had six children, and reunited in 1985 at a house in Moorhouse Street, Willagee.
Between October 6 and November 4, 1986 they took four young women off the street or by offering lifts, chained them to a bed in the spare room, raped them repeatedly over hours or days, and killed them. Mary Neilson was twenty-two, Susannah Candy fifteen, Noelene Patterson thirty-one and Denise Brown twenty-one. The bodies were buried in the Gnangara pine plantation and in bushland at Wanneroo.
On November 10 they took a seventeen-year-old at knifepoint. David Birnie went out to work and left her chained; Catherine untied her briefly, the telephone rang, and the young woman got out through a window with a chain still on her neck and ran to a shopping centre in Fremantle. She gave police the address.
Both confessed and led detectives to the graves. Both pleaded guilty in February 1987 and were given four life sentences, and the judge recommended they never be released. David Birnie hanged himself in his cell at Casuarina Prison on October 7, 2005.