Tell No Lies by Gregg Hurwitz
Paperback in very good condition.
Cover price is $11.99, asking $4.00.
From the back cover:
Daniel Brasher left a high-paying job as a money manager to marry his community-organizer wife and do the work he loves, leading group counseling sessions with recently paroled violent offenders. But just before his last day on the job, Daniel finds an envelope in his department mailbox - one intended for someone else, placed in his slot by accident. Inside is an unsigned note that says only "admit what you've done or you will bleed for it" along with a midnight deadline . . . which has passed. And Daniel quickly discovers that the person to whom it is addressed has already been brutally murdered.
Soon Daniel finds more warnings in his office mail, to people that the police cannot track down, and to victims that cannot be saved. Daniel's efforts, however, have alerted the killer to his involvement . . . and the next threat he receives is his own. Now, Daniel - with no clue what he's supposed to have done or what he must confess - must somehow appease or outwit a seemingly unstoppable killer. And time is running out.