Six Days of the Condor by James Grady (The Condor #1)

CIA operative Malcolm, code-named Condor, discovers his colleagues butchered in a blood-spattered office, he realizes that only an oversight by the assassins has saved his life. He contacts CIA headquarters for help but when an attempted rendezvous goes wrong, it quickly becomes clear that no one can be trusted. Malcolm disappears into the streets of Washington, hoping to evade the killers long enough to unravel the conspiracy—but will that be enough to save his life?

Paperback, 1975

Goodreads: 4.08