|Title||Assistant District Attorney|
|Affiliation||Manhattan District Attorney's Office (1987-1997)|
|Division||Manhattan Special Narcotics Bureau (1987-1997)|
|Pathology|| Corrupt ADA|
|Family|| Lisa Harmon (wife)|
Sophie Harmon (daughter)
|Actor||David Marshall Grant|
Harmon graduated from Columbia University alongside Jamie Ross and they became friends throughout their careers. While Ross became a defense attorney, Harmon became a prosecutor. At some point in his life, he married a woman named Lisa and they had two children. He worked in Brooklyn until he transferred to the Special Narcotics Bureau of the Manhattan DA's office. One day, he decided to take bribes from a defense attorney named Arvin Baker to drop cases on purpose and had his wife unintentionally help him with the profits. They charged $50,000 for each case, half at the beginning and half when they go to trial. and as a result, Gregory Billups, Geraldine Smithson, Corey Black, and four others got their cases dismissed after paying Baker and Harmon. Delmore Walton paid them $25,000 and was sent to prison when he couldn't get the other half of the payment.
While he was prosecuting a case against Elias Camacho for drug possession, he is approached by Ross, who now worked for the DA's office. She asks to take Elias off his hands when he is suspected of shooting Nancy O'Neal. He agrees, since the drug case was bound to lose. However, he says that he wants to participate in a murder trial next time and Ross agrees. (L&O: "Harvest")
When a bail bondsman named Manny Ehrlich caught onto the jury-rigging scheme, he tries to extort Harmon and Baker for a piece of the action. During a meeting between the two of them and Ehrlich, Harmon shoots him in the head and steals all of the money out of his desk. When Detectives Briscoe and Curtis question him on one his drug cases who skipped bail and one of Harmon's clients, Oscar Liriano, Harmon gives them some background and then asks what its about. They inform him of Ehrlich's murder and they drop hints they are looking at Liriano for the murder and Harmon decides to use it to his advantage. He later runs into Ross in the elevator as part of his plan to insert himself into the investigation. He does so by bringing up the Camacho case as a past favor.
When the police arrest Oscar Liriano for Ehrlich's murder, Jamie returns to tell him that she made him lead prosecutor on the Liriano case. He starts prepping Lennie for cross-examination and intentionally gives him bad advice to have the search suppressed. At the hearing, Harmon sets up Detective Briscoe to fail and the search is initially suppressed until Harmon references a sum of stolen money in the bag, to which it is reintroduced. After this, the police and Jamie realize Harmon killed Ehrlich since only the killer would know about the stolen money from the desk. They subsequently arrest him in front of his wife and children.
It is later revealed that the prosecution was a farce to reveal the corruption in the system and his attorney manages to suppress everything found. Harmon threatens to question every conviction he got if they do not accept a plea of manslaughter in the first degree. When Ross uncovers Lisa's involvement in the scheme, he accepts a plea of one count of murder in the second degree and nine counts of bribery while his previous convictions not connected to the fraud are excluded. He defends his actions as taking money from drug dealers to support his family. When Ross counters with the fact he could have come to her, he is silent. (L&O: "Shadow")
Harmon later filed an appeal and set a hearing to discuss the issue of bail before the Appellate Court. McCoy argued against his bail at the hearing and he was ultimately denied bail. (L&O: "Disappeared")