Dark Debts — Karen Hall

WHERE MURDER AND INSANITY WAIT...
Los Angeles journalist Randa Phillips assumed it was all over -except for the pain. But then came a midnight phone-call from the ex-lover who had rejected her. Responding to Cam's desperation, Randa heads out to meet him...but discovers he has meanwhile killed himself after an outburst of berserk violence. Two of his brothers had already died in horrifying circumstances - one of them in the electric chair,
Pressed on by instincts she cannot identify, Randa sets out to trace the last surviving brother. In a small rural town in the southern state of Georgia, she finds Jack Landry living the life of a haunted recluse. And Randa begins to sense there is more afflicting this tragic family than merely bad luck and wayward genes. For the entire Landry bloodline seems prey to a vengeful demon - picking them off one by one.
As this incredible menace intensifies, Randa finds an unexpected ally in a handsome Jesuit priest whose faith has been severely shaken, Before it's too late for Jack, they must accept the fact that their true enemy is Evil in its most violent and destructive form...