Nearly 200 people since 1973, mostly men, have never been identified in Maricopa County. Officials point to the prevalence of immigration, homelessness, mental illness and drug abuse that can separate people from their families and make it harder to identify them when they die.
As a result, families never find out what happened to their loved one, and, in cases of murder, police are hard-pressed to catch the killer without knowing the victim's name.
It's a problem that extends beyond Arizona. About 5,000 unidentified remains have been placed in the National Crime Information Center database, and some officials estimate that more than 40,000 other bodies nationwide are unidentified.