In several Bantu languages in the regions where Kikongo and Lingala are spoken, we encounter sentences where the word 'person' can appear after the subject of a canonical SVO sentence, resulting in a focused interpretation of the subject. Synchronically, we analyze this as a monoclausal focus construction with moto 'person' as a focus marker. Diachronically, we argue, the construction derives from a biclausal cleft, where moto functioned as the head noun of the relative clause. This is a crosslinguistically rare but plausible development. The different languages studied in this paper show variation in the properties indicative of the status of the 'moto construction', which reflects the different stages of grammaticalization. Finally, we show how contact-induced grammaticalization is a likely factor in the development of moto as a focus marker.