A robbery victim died after he was stabbed in the head with a screwdriver while trying to get his mobile phone back.
Police believe Keith Soons was attempting to recover his iPhone 4 when he suffered fatal head injuries in an assault in Cheltenham, Gloucestershire.
The 36-year-old, from Gloucester, was found by a member of the public in Wellington Lane at around 8am on Saturday.
Mr Soons, father to a two-year-old daughter, suffered serious head injuries. He was taken to hospital but died later that day.
Detectives said Mr Soons' mobile phone was missing and they believe he may have been killed as he tried to get it back.
Detective Superintendent Simon Atkinson, who is leading the murder investigation, said: "This is a tragic case where it appears a man has tried to retrieve his stolen property and, in doing so, received fatal injuries.
"Preliminary post-mortem results show that Mr Soons is likely to have died from a penetrative puncture wound to the side of his head. It is too early to say exactly what caused this but it is thought to have been a screwdriver-type implement."
More than 30 detectives are working on the investigation and house-to-house inquiries are continuing.
Mr Atkinson said: "We know Mr Soons' mobile phone is missing, it was an iPhone 4 and we are appealing to anyone who may have recently been offered one of these for sale, or knows someone who may have unlawfully obtained one, to contact us," Mr Atkinson said.
"Also, those responsible could well have been injured or have blood on their clothing. We are appealing to anyone who has knowledge of those involved to get in touch."
