Grooms was a federal agent with the Bureau of Alcohol, Tobacco and Firearms, and later the Federal Bureau of Investigation. Assigned to San Francisco, he headed the investigation into the bomb murder of Amanda Babbage. Inclined to dismiss Leland Stottlemeyer as an amateur and Adrian Monk as an oddity, he quickly hit on Amanda's kid brother Ricky as the likely suspect, since he was the only person with a motive who could have sent the bombs. Grooms was amused and derisive when Monk suspected the elder brother, Brian, who had been in a coma for four months. However, Monk was eventually proved right, and the agent gained a new respect for his abilities.
Grooms later handled a federal investigation into organized crime connections with a local labor union, headed by Harry Bolston. He inadvertently stepped on Stottlemeyer's toes when Bolston cooperated willingly with the federal investigation, while Stottlemeyer suspected one of his thugs of critically injuring Stottlemeyer's wife, Karen.
Grooms was later involved in the Jack Whitman case where he was searching for proof that Whitman was running an illegal arms dealership. Stottlemeyer managed to find it in the form of a paperjam, and mentioned that he was going to deliver it to him.
At some point, Grooms transferred to the FBI. He was assigned to take Monk into protective custody after Monk witnessed Chinese gangster Tommy Win commit cold-blooded murder. The plan unraveled, but Grooms managed to surprise and shoot one of two hit men sent after Monk.