The records of the unclaimed dead are kept in a fireproof safe at the County Crematorium. Although a project to digitize those records is underway, they are currently kept in bound books. Hence this episode's title, "Book of the Unclaimed Dead."
Since 1896 in Los Angeles County, there have been nearly 2,000 men, women, and children whose bodies were never claimed and whose cremated remains were eventually buried in a mass grave in the County Cemetery in Boyle Heights.
The actor who plays Lieutenant Bob Torres in the diner scene with Robertson is Daniel Steven Gonzalez. Before pursuing an acting career, Gonzalez was a paramedic and firefighter for 10 years in the Los Angeles Fire Department.