Thе study explores the interaction between the participants in the communication process with respect to their knowledge about the situation presented in the utterance when transforming direct into indirect speech using a verbum dicendi. The speaker has a choice between firsthand (indicative tenses) which by definition denotes a witnessed situation and non-firsthand which presents the situation as non-witnessed. The interplay between the grammatical marking and the speaker’s evidential strategy is analyzed by applying a corpus method. The data of the Bulgarian National Corpus are used to detect the preferences for a given strategy considering also the grammatical person which indicates the level of knowledge of the communicants about the situation: the 1st person shows the strong knowledge of the speaker, the 2nd person is related to the strong knowledge of the listener, and the 3rd person is associated with a weak knowledge of both participants. Illustrative examples representative for a given situation are extracted from the corpus and subjected to a context analysis.