Necromancer Amulet (Skyrim)

Initially called the Strange Amulet, it is found on a bookshelf in Hjerm in Windhelm as part of the quest Blood on the Ice.

Obtaining the Amulet

 * 1) Sell the Strange Amulet it to Calixto.
 * 2) Go to Wuunferth, the court mage and he'll identify it as the necromancer's amulet. He will suggest patrolling the streets at night for the Butcher.
 * 3) Wait till night and start walking around the slums and and market place. You'll see Calixto attempting to murder a woman, do not stop him.
 * 4) Wait till it says "catch the killer" and Calixto will head back to the Hjerm.
 * 5) Kill Calixto in Hjerm and search search his body for the Amulet

Bugs

 * 1) Accusing the Mage of being the murder will make you unable to obatin the Amulet