This article focuses on the controversial issue of apostasy pertaining to the alleged family of Shaykh Yusuf of Makassar, the Indonesian pioneer of Islam in colonial South Africa, after his demise at the Cape in the late 17th century during a period of Dutch occupation of both countries. It is reported in local and international historical and scholarly sources that the second generation grandchildren of this political exile and learned Islamic scholar converted from Islam to Christianity at the Cape and thereafter entered into marriages with Christian spouses. Their mother is alleged to have been the Shaykh’s daughter, Zytie Sara Marouff (alias Care Sale), and their father, the Rajah or King of Tambora (alias Abulbasi Sultan), a fellow exiled countryman. The marriage between the Rajah and Zytie is alleged to have taken place shortly after his arrival at the Cape in 1698 but before the death of Shaykh Yusuf in 1699. The conversions are recorded to have taken place within two decades of the Shaykh’s death and shortly after the death of their father, the Rajah, in 1719; both averted death sentences but died during exile at the Cape. The main aim of this article is to critically analyse these sources, which contain both conflicting information, and whose authors express ambivalent views, in an attempt to unravel the mystery surrounding their conversion and the marriage of their parents. Although some local Muslim religious authorities (ulama) at the Cape are aware of these conversions, many are not. In fact, these conversions were overlooked in a publication on the very topic. Local Muslims have therefore not been fully apprised by them of this aspect of their history because the topic is understandably also a sensitive one. The aim of this article is therefore not to dispute these facts or even that these conversions may have been a voluntary exercise and a consequence of freedom of choice. Although an analysis of some of the policies of the then Dutch colonial government which were enforced at the Cape (for ...