A man died on New Year's Eve after being attacked in the street by a stranger wearing a party hat.
Christopher Mason, 30, was walking with his girlfriend in Market Street, Watford, Herts, when he was assaulted.
A police spokesman said Mr Mason, who lived in the town, was punched in the face and hit his head on a brick wall as he fell early on Christmas Day.
The attacker, who is described as white and about 6ft tall, was wearing a gold Christmas party hat.
He made off in the direction of Casio Road.