Deck the Hounds

Andy Carpenter's good intentions lead him into murder and intrigue. When he stops to give a homeless man $20 and a gift card from PetSmart, he assumes that is the end of his encounter with the man. In Deck the Hounds by David Rosenfelt, Andy  learns the man he helped was attacked and his dog bit the attacker.

He decides to help get the dog back to the owner. This leads him to offer the homeless man and his dog the apartment above the garage. Don Carrigan and Zoey move into the garage, but before long the police show up to arrest Don for murder. 

About nine months ago a wealthy business executive named Steven McMaster was murdered in his home and valuables were stolen. A hat at the scene has DNA evidence that links it to Don. A background check on Don finds he was a former Green Beret and veteran of the Iraq invasion. He was specially trained and could very easily have broken McMaster's neck. When a ring stolen from McMaster is found in Don's locker at a homeless shelter, the police think they have a slam dunk case.

Andy knows the interview he gave to the newspaper, mentioning Don by name is what got him arrested, so he and his investigator wife Laurie try to find the real killer. 

The police find themselves occupied with finding a sniper who killed a prominent attorney.  When another sniper murder takes place, Don Carrigan's investigation is relegated to Andy and Laurie.

Piecing together the reason for the first murder, Andy finds some intriguing connections between the McMaster murder and the sniper killings. An elegant puzzle that leads to a killer. Excellent book.

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