In Curse Of Strahd, his body was found by a group of adventurers later called the Heralds of Dawn. They placed him in a Bag of Holding and took his body to the Burgomaster Dmitri Krezkov, who had him buried behind the Krezk Burgomaster's Cottage.
Raised as a Sheep-herder in Krezk, Costel had a quiet and frightful spirit. His parents died from illness when he was young, making him the de-facto caretaker of the Barbu Farmhouse as well as his younger brother Oleg Barbu. Despite Oleg's ability to commune with animals, Costel resented his dual responsibilities as shepherd and caregiver, and turned to wine to get him through the cold Barovian nights. Generally unpleasant to be around, he never married or had children.
By 735, Costel was pained due to the infrequency of wine shipments from the Wizard of Wines, which had been growing increasingly intermittent. Fueled by addiction and desperate for a solution, he braved outside the village walls on his own, looking to figure out what was happening to the winery. He torn apart by a Wolf pack before he had even made it to the Raven River Crossroads, lasting about a half-day's journey on his own.