He was born early in the thirteenth century to a peasant family in the village of Basarov, then part of Bulgaria. Even in childhood, he gave himself to fasting and prayer. Once, walking across a field, he accidentally stepped on a bird's nest in the grass, killing the young birds. He was so filled with remorse that he went barefoot for three years, winter and summer, in penance. When he was grown he joined a monastery and, after a few years of community life, received a blessing to dwell in a cave near the River Lom. After many years of solitary struggle, he reposed in his cave. Three hundred years passed, during which all memory of the simple ascetic was lost. Then, one Spring the river flooded the cave and carried off Demetrius' body, which had lain incorrupt in the cave for centuries. The body was carried downstream and buried in gravel. Another hundred years went by, and the Saint appeared in a dream to a paralyzed girl, telling her to ask her parents to take her to the river bank,