C.I.A. operative in Honduras, and the only agent available to aid the S.G.C. when Drs. Daniel Jackson and Bill Lee went missing. Burke had formally requested that Jack O'Neill be assigned to participate in the extraction process. Burke was aware of the last place Jackson was seen -- an outdoor cafe -- and met O'Neill at that location. He also knows how to get across the borders, and how the Honduran rebels operate.
Burke was hoping to put aside his checkered past with O'Neill. The two had once been good friends, along with an officer named Woods and his wife, Cindy. Originally Burke claimed that Woods had been a hostile when he "accidentally" shot their ally, and that the two chose to improvise in the field at the same time (they had been out of their designated positions). In truth, Woods had sold out the team, sending rogue transmissions to their enemies. Woods had realized Burke was on to him and turned his weapon on Burke, who consequently killed him. Burke finally told this to O'Neill, who gradually began to accept the truth.
Burke's wife at the time was a woman named Hillary, who likely left him following the incident. He was crushed, and found solitude in Honduras -- but that only lasted for a time. Following the successful retrieval of Jackson and Lee, O'Neill recommended Burke be reassigned to a more temperate climate.
Evolution, Part 2 - Burke's aid is required by O'Neill to locate Jackson and Lee, who have gone missing in Central America; Burke is determined to lay aside all personal differences and regain his friendship.