When conducting medical field research in a Luo village in western Kenya, my colleagues and I were occasionally suspected of being blood-thieves, locally called kachinja. The article contextualizes these blood-stealing accusations within the practices of medical research that prompted them, and within the local historical experiences which, I shall argue, they refer to. Further, it examines two social situations, in which blood-stealing accusations were raised against me and people who were in contact with me, in order to show how the kachinja idiom is used in social practice, as part of long-term social processes as well as of momentary situations, within local patterns of relatedness. These observations show how global structures and processes are articulated and moulded in a particular locality through idioms that carry memories of individual as well as collective, historical experiences, and how they are enacted by people within webs of contemporary local social relations.