Police are investigating whether murder victim Joanna Yeates could have been strangled with her own ski sock -- which her killer might then have kept as a trophy.
The landscape architect's snow-covered body was found on Christmas morning missing one of her grey, knee-length socks, and detectives believe the garment may hold the key to solving her murder.
The 25-year-old -- last seen alive nearly three weeks ago -- was not wearing her coat or boots either but those items were recovered from her flat in Canynge Road, Clifton, Bristol.
Det Chief Inspector Phil Jones, who is leading the murder hunt, held up a similar size-five sock to the one Miss Yeates was wearing.
He said: "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 (where her body was) and it hasn't been found at her home."
The detective said he was "keeping an open mind" about whether the killer or killers could be keeping the sock as some sort of trophy or whether Miss Yeates was strangled with it.
Following the appeal for the missing garment -- the type bought in an outdoor shop -- a man approached police outside Miss Yeates's flat and handed over a grey sock.
The sock was put into an evidence bag but later police said at this stage it was not the sock they were looking for.
Mr Jones also confirmed that the killer or killers may have tried to put Miss Yeates's body over a wall into the quarry on Longwood Lane, Failand, North Somerset, but instead left her on the grass verge.
"There are a number of theories about how Jo came to be in Longwood Lane and this is a possibility, yes," he said.
Mr Jones would not confirm directly that police were using a criminal profiler but said his team were receiving assistance from various expert sources.
"We continue to use all the available professional resources available to us," he said. "This is a complex and meticulous investigation that will leave no stone unturned.
"I can assure you that we will find Jo's killers."
Police said that since an advert was placed on Facebook on Tuesday it had been viewed nearly 250,000 times. There have also been more than 70,000 views of the appeal on the police website and more than 120,000 views of CCTV footage on YouTube.
After another appeal earlier this week, a couple of motorists who had been driving 4x4 vehicles in the Longwood Lane area on the night Miss Yeates disappeared have come forward but police appealed for others to get in touch.
The landscape architect was last seen walking back to the rented flat that she shared with her boyfriend Greg Reardon (27) after going for drinks with colleagues on December 17.
She visited three shops on the way home and was filmed on CCTV buying a pizza in Tesco Express, Clifton. The receipt was discovered in her flat but no evidence of the pizza or the packaging has ever been found.
Miss Yeates was found three miles from her home by a couple walking their dogs on Christmas morning. She had been strangled.
Miss Yeates's landlord, retired Clifton College teacher Chris Jefferies (65) was arrested on suspicion of her murder, but freed on bail after three days of questioning.