Cross Fire by James Patterson

Cross Fire is a Alex Cross novel in a series of books written by James Patterson.
Wedding bells ring: Detective Alex Cross and Bree's wedding plans are put on hold when Alex is called to the scene of the perfectly executed assassination of two of Washington D.C.'s most corrupt: a dirty congressmen and an underhanded lobbyist. Next, the elusive gunman begins picking off other crooked politicians, sparking a blaze of theories--is the marksman a hero or a vigilante?
A murderer returns: The case explodes, and the FBI assigns agent Max Siegel to the investigation. As Alex and Siegel battle over jurisdiction, the murders continue. It becomes clear that they are the work of a professional who has detailed knowledge of his victims' movements--information that only a Washington insider could possess. As Alex, caught in a lethal cross fire, contends with the sniper, Siegel, and the wedding, he receives a call from his deadliest adversary, Kyle Craig. The Mastermind is in D.C. and will not relent until he has eliminated Cross and his family for good. With a supercharged blend of action, deception, and suspense, Cross Fire is James Patterson's most visceral and exciting Alex Cross novel ever.
Alex Cross is an African-American detective and psychologist living and working in the Southeast quadrant of Washington, D.C. He works in the homicide division of the Metropolitan Police Department of the District of Columbia (MPD), but eventually becomes a Senior Agent with the Federal Bureau of Investigation (FBI)... (Summary by Wikipedia)