This paper deals with a prosecutor's closing argument in a murder trial I did fieldwork on in California in 2000. This discourse is analyzed through the conceptual blend of the deceased victim 'testifying' through legal evidence. The emergence and argumentative power of this blend is examined vis à vis the participants' knowledge of the embedding discourse and trial as well as their conceptualizations of what a trial is. I suggest a definition of a trial as a 'semantic network' (Langacker, 1987), which combines lawyers' common definitions with the nature of factive and fictive interaction in Western courts (Pascual, 2002, 2006). The claim is that language users (meta)operate with intertwined layers of context conceptualization, constraining conceptual blending operations. The paper integrates cognitive linguistics with cognitive sociology (Cicourel, 1973) and cognitive and linguistic anthropology (Hutchins, 1990; Duranti, 1997). It also calls for the qualitative study of language through in-depth enthnography that ensures data validity. © John Benjamins Publishing Company.