Yankee in the Wind by Tina Folsom

When investigating the death of his fellow Stargate agent, Jack “Yankee” Porter meets the dead man’s cousin, Lilly Davis, who’s questioning the circumstances of her cousin’s death. Following the clues, Yankee and Lilly must realize that the mysterious Mr. Smith, who’s been hunting former Stargate agents, has something even more nefarious in store for the agents of the now defunct top-secret CIA program—not to kill them, but to use them for his own evil purpose.