House witness
(Book)

"Minority Leader of the House and DeMarco's long-time employer John Mahoney has kept more than one secret from his wife over the years, but none so explosive as this: He has a son, and that son has just been shot dead in a Manhattan bar. Mahoney immediately dispatches DeMarco to New York to assist prosecutor Justine Porter, but with five bystanders willing to testify against the killer--rich-boy Toby Rosenthal--the case seems like a slam-dunk. That is, until Porter begins to suspect that someone is interfering with those witnesses, and that this may be connected to a pattern of cases across the country. Is there someone who is getting witnesses out of the way when the fate of a wealthy defendant is on the line? With the help of Porter's young and brainy intern, and traveling from New York to Las Vegas, Minneapolis, Phoenix, and beyond, DeMarco becomes determined to follow that question through to its violent resolution" -- From dust jacket.