Shadow of the Moon. Shadow SEALs, #6

Devlin Kreed used to be one of the best Navy SEAL snipers in the business. They called him Moon Devil, because he preferred to hunt his targets during the darkest part of the night. When he took out a high-value target, his career disintegrated. The SEALs kicked him out the door as a liability. It had all been a ruse, though, part of a CIA relocation op. The CIA promised him they would have his back, but they hung him out to dry, letting him take the fall for killing the target.
Now, there's a voice on the phone offering him an astronomical amount of money to take out the same man again. Because the CIA messed up. While trying to extract information, the murderer escaped them, and the world is now a much more dangerous place. CIA agent Amberly Temple knew something was hinky as soon as the folder hit her desk. It was a cold case, but one of the most high-profile ones in her department, and she suspects a dirty agent.
She must be getting close because as she tracks down witnesses and backtracks the investigation, someone tries to take her out. Luckily her former SEAL ex-husband is there to save her ass...