Officers probing the death of Ritvars Kozans also confirmed that a total of four people had now been arrested in connection with the 22-year-old's murder.

Mr Kozans, who was found at flats in Woolmonger Street, Northampton, at about 9.40am on Friday, is known to have visited pubs and clubs in the town on Thursday night.

His death was initially treated as unexplained, but a post-mortem examination showed that he had suffered a bleed to the brain which was unlikely to have been the result of natural causes.

Two men aged 20 and 40 and two women, both 19, are helping police with inquiries.

Detective Chief Inspector Jan Meagher, who is leading the murder investigation, said: "We know Ritvars was a hard-working, sociable young man.

"He was out and about in Northampton on Thursday evening and into the early hours of Friday and I need to speak to anyone who knows where he was, who was with him or who saw him."