David John Birnie (16 February 1951 – 7 October 2005) and Catherine Margaret Birnie (née Harrison; born 23 May 1951) were an Australian couple from Perth, Western Australia, who murdered four women at their home in 1986, and attempted to murder a fifth. These crimes were referred to in the press as the Moorhouse murders, after the Birnies' address at 3 Moorhouse Street in Willagee, a suburb of Perth.