Question: Whose murders did voldemort use to create each of the Horcruxes?
J.K. Rowling: The diary - Moaning Myrtle. The cup - Hepzibah Smith, the previous owner. The locket - a Muggle tramp. Nagini - Bertha Jorkins (Voldemort could use a wand once he regained a rudimentary body, as long as the victim was subdued). The diadem - an Albanian peasant. The ring - Tom Riddle senior.
-- Bloomsbury Live Chat (BLC)
After stealing Salazar Slytherin’s locket from Hepzibah Smith, Tom Riddle used the murder of a Muggle tramp to turn the locket into a Horcrux with part of his soul inside (BLC).