Marele Day grew up in Sydney and graduated from Sydney University with BA (Hons). Her work experience ranges from fruit picking to academic teaching and she has travelled extensively, taking up temporary residence in Italy, France and Ireland.

The Life and Crimes of Harry Lavender (1988) was Marele Day's first thriller, followed by The Case of the Chinese Boxes (1990), The Last Tango of Delores Delgado (1992) which won the 1993 Shamus Crime Fiction Award, and The Disappearances of Madalena Grimaldi (1994). In 1996, Day was the general editor of and contributor to How to Write Crime. And in 1997, Day published her bestselling literary novel, Lambs of God, to acclaim in Australia and overseas.