This article examines the inquisition against Botulf, the only person known to have been executed for heresy in medieval Sweden. It analyses the tactics of evasion that Botulf employed to escape detection and apprehension by tapping into common conceptions of the Eucharist to gloss his dissent. Through a close reading of the sentence in its historical, cultural and liturgical context, the article argues that it not only records a unique case in medieval Sweden, but that it performs clerical and elite identities by drawing on biblical and liturgical topoi, as well as antiheretical rhetoric to depict Botulf as a ‘membrum diaboli’.