Inquisitor Demetrio was responsible for investigation and law enforcement in the city of Numalia. He is a cunning, perceptive man, setting him apart from more bloodthirsty guardsmen. Although strong of will and intimidating, he does not let his pride get in the way of an investigation. However, he does allow circumstances to interfere with the just application of the law.
During the events of "The God in the Bowl", Demetrio investigates the murder of Kallian Publico. After examining the evidence, he becomes convinced that Conan is not the killer, and does not allow the guards to simply arrest him and leave the real killer at large. However, he allows Conan to remain armed and free during the investigation to avoid provoking him. Later, when it becomes clear that the nobleman Aztrias Petanius is involved in the theft, he talks of allowing Conan to escape to prevent any embarressment to the important young man or his family.
Demetrio is tall, and wears his head shaven. He is often clad in the robes and chain of his office. Although he was not killed during "The God in the Bowl," he was stabbed through the leg and walks with a limp.