Once thought of as a political genius, Gavin was a rising star, until he was fired from a Carolina senator's reelection campaign after allegations of embezzlement were made. Lloyd was never indicted for the crime, but he was blacklisted by both major political parties.
Seeing an opportunity to climb back, he attached himself to St. Claire, and became his trusted right hand man in the campaign. Unfortunately, he reverted to old habits and couldn't resist filching campaign funds. His fraud was discovered by volunteer Nicole Vasques, who confronted him, and whom he unsuccessfully tried to bribe into silence.
Panicking, Lloyd then tried to hire St. Claire's bodyguard, Jason Ronstadt, to kill Vasques. When Ronstadt turned him down, Lloyd now had two problems to eliminate. He managed to stall Vasques and Ronstadt until he found a professional killer, Ian Sykes, to kill both of them. The killing of Ronstadt was made to look like a failed assassination attempt on St. Claire - which hid the true motive for the shooting, and, as an added bonus, boosted St. Claire's heroic image for the campaign.
Gavin's mistake, however, was to overplay his part in the shooting, pointing excitedly at Sykes's sniper's nest, when in fact it was impossible for anyone else to have known exactly where the shots came from. This discrepancy was eventually uncovered by Adrian Monk.
In the course of Monk's investigation, Lloyd became nervous, and hired Sykes for another killing, of a campaign volunteer named Jake, who had discovered proof of the connection between Vasques and the campaign. Lloyd also attempted to kill Monk himself, trying to run him down in a car, though Monk escaped.
Shortly thereafter, when the SFPD managed to locate Ian Sykes, he secretly made a call to Sykes, urging Sykes to meet with him at the docks. When Sykes arrived, Lloyd shot him to cover his tracks (and possibly to avoid having to pay Sykes the balance of his fee). Unknown to him, Sykes survived the gunshot wound.
Lloyd was confronted at the scene of the shooting by Monk and the SFPD. He tried to brazen it out, until Monk demonstrated, graphically, that no one but the man who hired Sykes could have known where the shots came from. Lloyd broke down and started to confess, but at that moment, Lloyd himself was shot by Sykes (in what Monk wryly called "a contract dispute").