The Devil's Teardrop by Jeffery Deaver ISBN 13: 9780671038441

New Year's Eve, 1999. After an early morning machine-gun attack by a madman man called the Digger leaves dozens dead in the Washington, D.C. subway, the mayor's office receives a message demanding twenty million dollars by midnight or more innocents will die. With the ransom note as the only evidence, Special Agent Margaret Lukas calls upon retired FBI agent and the nation's premiere document examiner Parker Kincaid, to join the manhunt for the Digger -- or for hundreds, the first moments of the new century will be their last on earth.