Murder victim Joanna Yeates could have been strangled with her own sock which her killer might have kept as a trophy.
Police believe the missing grey ski sock may hold the key to solving the murder of the landscape architect whose snow-covered body was found on Christmas morning.
Det Chief Inspector Phil Jones, who is leading the murder inquiry, has not ruled out the possibility the 25-year-old's killer may have used the sock to strangle her or that they kept it.
Miss Yeates was found dead in Longwood Lane, Failand, North Somerset, wearing just one sock.
She was not wearing her coat or boots either but those items were recovered from her flat in Canynge Road, Clifton, Bristol.
Holding up a box containing a similar long, ski-style size five grey sock, Mr Jones said: "I am here this morning to talk to you about a missing sock.
"When Jo was found on Christmas Day morning in Longwood Lane, although she was fully clothed, she was not wearing her jacket, she was not wearing her boots and she was only wearing one sock.
"The jacket and the boots have been found at her home address. That would indicate that Jo had returned home.
"However, at this present time the sock has not been found. It hasn't been found at Longwood Lane and it hasn't been found at her home address.
"It is described as a light grey sock with lighter detail on the toes, heel and shin."