Human sacrifice in ancient Mesoamerica was strongly linked with ritual behaviour and mythical beliefs. Yet it is rarely possible to explain the mythical associations of archaeological deposits derived from human sacrifice. In this article, we integrate archaeological, taphonomic and isotopic analysis to reconstruct the ritual behaviour that resulted in the formation of a partially cremated primary burial at the Lowland Maya city of Tikal. Taphonomic reconstruction reveals details about the form of death and combustion of two males, while isotopic studies hint at their probable geographic origin. To explain this ritual, we assess the relevance of widespread Mesoamerican mythical beliefs about the origin of the sun and the moon, and discuss the theoretical and methodological issues involved in this comparison. The burial's association with an E-Group compound makes it significant for the interpretation of these specialized architectural arrangements in southern Mesoamerica. It also pertains to a critical period in Tikal's history, marked by intensified cultural and political interaction with the highland Mexican city of Teotihuacan, manifest in this burial by the presence of imported green obsidian spear points. We propose that this unique context resulted from a sacrificial reenactment of the mythological birth of the sun and the moon.