The Heirloom by Edita A. Petrick

Dr. Amelia Rimgold is about to testify in a generic drug fraud. Two days before she's scheduled to go before the House Committee, she's shot during an intermission at the New York Fowler's Opera. The hit man takes the victim's antique gold locket. The locket is an heirloom and once belonged to the victim's ancestor, executed in Salem. The locket extends protection over the female descendants of the Salem Witch. Unknown to the hit man Amelia survived. The FBI is now hiding a double-witness in a safe house on the Maryland seacoast, under a new identity. But the locket wants to return to its rightful owner and is drawing the hitman back to the scene of his last crime.