Kostas was a farmer in Abrostola. Like others, Kostas had a motive for murdering Theodore: the previous year, Kostas and Theodore had exchanged plots of land. Kostas quickly became convinced that the land he'd received was inferior to the plot he gave Theodore. He acknowledged the fact that the Farmers' Law would have been on his side to Father George, and insisted he wasn't the killer.
However, Father George later deduced who the killer was and Kostas, armed with a sword and shield, accompanied the procession of armed villagers going to apprehend the killer.