Dead End by Lisa Phillips

COLD CASE INVESTIGATION 

Nina Holmes won't rest until she finds her mother's killer–and proves that her father was wrongly convicted. And now that she's left the CIA, she finally has time to pursue the case that shattered her childhood. But someone realizes that Nina's digging into the past, and soon it's her own life that's in jeopardy. Deputy US marshal Wyatt Ames is just as determined to keep Nina safe as he is to keep investigating. But as he helps her with the case, they discover that this killer may be even more dangerous than anyone expected. And to capture him, Wyatt and Nina must be willing to do whatever it takes–even use themselves as bait.