The Department of Justice reports in the year 2004 in California there were 37,809 adult persons reported missing.

The Los Angeles Police Department, Missing Persons Unit was established in 1972 when the need for specialization in missing persons investigations was first recognized. The Missing Persons Unit has citywide responsibility for the investigation of adult missing persons. Missing persons investigations can present a genuine challenge to the law enforcement community. Detectives assigned to the Missing Persons Unit have a high level of expertise and are selected to work this assignment from other divisional geographic detective divisions. Detectives from the Los Angeles Police Department will investigate each missing person case that is reported.