Conviction (Christopher Paget #4) by Richard North Patterson
 
When the body of eleven-year-old Thuy Sen is found in San Francisco Bay, the police swiftly charge Rennell and Payton Price with her grisly murder. A twelve-person jury, helped along by an incompetent lawyer for the defense, are quick to find the brothers guilty - and to sentence them both to die for their crimes.

Twelve years later, Payton is days from his execution, and overworked pro bono lawyer Teresa Peralta Paget, her husband Chris, and stepson Carlo, a recent Harvard law graduate, become convinced not only that Rennell didn't receive a fair trial, but that he's innocent. Racing against the clock and against insurmountable legal obstacles, Teresa, Chris, and Carlo desperately try and stop the execution of an innocent man.
 
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