Martha "Marty" Gessler was an agent with the FBI's Los Angeles field office. She was single, lived in Sherman Oaks, and had two dogs. She was nearly 6 ft. tall and weighed 140 lbs. She was strong and trained in self-defense. She typically wore her weapon in a holster on her hip. Initially she was a field agent in the bank robbery division where she worked with Eleanor Wish in the late 1980s. They were the only two women in the unit at that time. Their most high-profile case was the capture of the "Two Step" bandit.
In the mid-1990s, she acquired computer skills that became increasingly important to the bureau. As a result her job description changed to crime analyst and she focused almost exclusively on using technology to solve crimes. In 1999 she began compiling a database of recorded currency serial numbers in order to cross-reference the bills from various robberies. After the armed robbery of two million dollars from a movie set, she contacted LAPD detective Jack Dorsey to inform him that one of the serial numbers from the movie set robbery actually belonged to a bill in evidence from an earlier bank robbery. This discrepancy could not be explained.
At some point in her FBI career she became romantically involved with another agent, Roy Lindell. This was against bureau policy so they kept their relationship secret.
On 19 March 2000, Gessler was abducted by two RHD detectives (Dorsey and Cross). Her disappearance was reported in the Los Angeles Times by Keisha Russell. At first her disappearance was not linked with the robbery, despite the fact that she had been working on the serial number discrepancy. There was very little evidence indicating what happened to her. Her size, strength and the fact that she was armed made her abduction all the more puzzling. Lindell attempted investigate and was told by the Department of Homeland Security to back off, which he did. When Harry Bosch revived the investigation into the murder of Angella Benton and the robbery, Lindell asked him to look into what happened to Gessler. Ultimately, Bosch uncovered the involvement of Dorsey and Cross, and he forced Cross to tell him where she was buried. Bosch and Lindell found her buried, along with her laptop computer, in a shallow grave in a remote part of Griffith Park.
- Lost Light (mentioned)