Horror On The Orient Express
Brother Merovac was a late 12th Century monk known for his occult lore. He travelled widely in the Middle East in disguise, studying secrets forbidden to infidels. When discovered, he fled the Muslim lands on pain of death. He was last known to have been in Constantinople in 1204, where he betrayed the trust of the Crusaders, stole the Simulacrum, and vanished.
It seems likely that “Merovac” was actually a false identity being used by the vampiric being later known as Count Fenalik.