This article examines gender representations of ‘single’ women accused of murder in mid twentieth-century England and Wales. Specifically, it identifies discourses of the ‘lesbian’ and the ‘spinster’ as they arose during the prosecution process. These discourses are outlined and placed within their wider socio-historical context. The appearance of different constructions of lesbianism and/or spinsterhood is analysed in relation to five women's cases, with reference to material from their case files. The examination of discourses of singleness reveals how it was often construed in the mid twentieth-century criminal justice system as connoting marginal, or deviant, gender identity in women. Single women did not fulfil contemporary norms of femininity relating to marriage and motherhood. However, representations of single women were frequently contested and contradictory, and in the cases under discussion also related to the type of killing the woman had carried out.