Carlos Aguila is an investigator with the Baja California's State Judicial Police. He is of partial Chinese ancestry from his grandfather who was brought to Mexicali in the early 20th century as a laborer. For this reason, other members of the SJP call him Charlie Chan. His supervisor at the time was Captain Gustavo Grena. Aguila is one of the few members of the SJP that was not on the payroll of drug lords.
In December of 1992, he issued a memo seeking information of a missing Mexicali man, Fernal Gutierrez-Llosa. This memo reached the LAPD where it came to the attention of Calexico Moore and then Harry Bosch. He assisted Bosch in determining that a murder victim found in L.A. was in fact Gutierrez-Llosa. He then assisted Bosch and the DEA in investigating EnviroBreed and the Black Ice drug operation run by Humberto Zorillo.