A man has been arrested after a body was found in a block of flats in Bedford.
Police said the death of the man, who was found shortly before 0200 GMT in the flats in Calshot Walk, was being treated as suspicious.
A Bedfordshire Police spokeswoman said results of post-mortem tests would not be known until Boxing Day but officers thought he may have been assaulted.
Detectives have urged anyone who saw anything suspicious to come forward.
Det Ch Insp Steve Collin said: "A man has been arrested and remains in police custody.
"We are still in the early stages of the investigation."
He appealed for anyone who was in or around the flats between 1800 GMT on Christmas Eve and the early hours of Christmas morning and who saw or heard anything possibly linked to the incident to contact police.