An attacker wearing a Father Christmas hat and beard stabbed a man to death in his home.
Police found the attacker's hat on Saturday morning
The knifeman wore the red and white hat and full white beard when he murdered Sikander Shaheen, 25, in Leyton, east London, early on Saturday, police said.
Officers found Mr Shaheen bleeding in his house after neighbours called them. He died soon after in hospital.
Police want information about the victim's movements after he came home from work on Friday evening.
Police said they have recovered the hat. The rest of his clothes were described as dark.
Mr Shaheen, an accounts manager, was a hard working, law-abiding, religious man, according to police.
Police are appealing for anyone who saw a man matching the attacker's description in the Grove Green Road area between 0530 GMT and 0700 GMT on Saturday to come forward.