Charlie Hovan is an agent with the U.S. Drug Enforcement Administration (DEA) and an expert in Armenian drug gangs. In 2017 he was investigating a Russian-Armenian drug gang operating in southern California. The leader of the drug gang was a man known only as Santos. During the investigation of the Esquivel double murder, Jerry Edgar recommended that Harry Bosch and the San Fernando Police Department work with Hovan to infiltrate the gang. By working together, Hovan could bring down the drug gang and the SFPD could solve the murder case. Hovan reported that Santos' base of operation was the Slab City area near the Salton Sea in Imperial County. He proposed that someone from SFPD go undercover to gather evidence on Santos, and Bosch volunteered for the job.