Sheehan had a unique way of starting an investigation. He kept an old milk crate in the trunk of his Crown Vic. At a murder scene he would place the crate in a strategic location, then sit on it to study the physical setting in which the crime had occurred.
In the late 1992 Sheehan was involved in a shooting incident in which he killed a suspect named Wilbert Dobbs. The shooting was ruled justified, but Sheehan and the department were sued by Dobbs' family, with Howard Elias representing them. Since this incident occurred just a few months after the Rodney King riots, the jury awarded damages to Dobbs' family. Sheehan took the verdict personally and made threatening statements about Elias.
In 1993, Sheehan publicly threatened civil rights attorney Howard Elias, telling the lawyer that someday, someone would sneak up behind him and put him down like a dog. In November of that year, Sheehan worked with Bosch, Hans Rollenberger, and Irvin Irving in pursuit of a recently-revealed killer whose murders had previously been creditted to the Dollmaker.
In June of 1998, Sheehan investigated the disappearance and murder of Stacey Kincaid, in the process of which he arrested Michael Harris. Sheehan participated in questioning Harris for three days, and when Harris refused to confess, Sheehan and three other homicide detectives beat him, placed a plastic bag over his head, and punctured his eardrum with a Black Warrior #2 pencil. Harris was later acquitted of the murder, and he filed a police brutality case against Sheehan and 14 other officers.
When they were partners in RHD, Bosch had always known Sheehan as a good and honest cop. There was a case from that time in which Sheehan could have justifiably shot a carjacker. Instead, Sheehan talked the man into surrendering. However, in later years Sheehan had changed. He confessed to Bosch that Harris had, in fact, been brutalized as stated in his lawsuit, but Bosch kept this information to himself.
In April of 1999, Sheehan was called to the scene of the murder of Howard Elias, who was at that time representing Harris in the police brutality suit against the LAPD. Sheehan, and all of RHD, was taken off the case because of extensive past conflicts with Elias. In fact, it was widely assumed that Elias's killer was a cop, and Sheehan became a suspect due to his previous threats against Elias. John Chastain took bullets from the Dobbs evidence box and submitted them for ballistics analysis in the Elias case in order to frame Sheehan. He was questioned by FBI agent Roy Lindell, but was released at Bosch's insistence. Since Sheehan's wife had recently left him, Bosch offered to let his old partner stay at his house for a few days. To Sheehan's horror, Bosch reveals that Harris, the murder suspect he tortured to learn the victim's whereabouts, is really innocent.
The news that a LAPD detective was a suspect in the murder of Elias was not unexpected, but it led to several days of protests and rioting. Sheehan was later murdered by Chastain with a gunshot to the head while Sheehan sat on the balcony of Bosch's house in the Hollywood Hills, arranging the body to look like a suicide. Although Bosch obtained proof that the ballistics analysis was false and Chastain was the real killer, the LAPD chose to portray Sheehan as the killer in order to restore peace to the city.
- The Black Ice
- The Concrete Blonde
- Angels Flight
- "Cielo Azul"
- The Black Box (mentioned)
- Two Kinds of Truth (mentioned)