Joanna Yeates may have been killed by more than one person, the detective leading the murder hunt said, as he confirmed her landlord remains a suspect.
Detective Chief Inspector Phil Jones said one “hypothesis” is that an accomplice helped whoever strangled the landscape architect, adding that he was “not making any assumptions” about how the crime was committed.
Scenes of crime officers continued to search the home of Christopher Jefferies, 65, the former English master who owned Miss Yeates’s flat in Bristol and lived in the same building, 48 hours after he was released on police bail.
Mr Jones said Mr Jefferies, the only person so far arrested on suspicion of murder, “is still a suspect” but refused to say whether any other suspects have been identified.
He also disclosed that witnesses had reported seeing a light-coloured 4x4 vehicle near the spot where 25-year-old Miss Yeates’s body was found on Longwood Lane, around three miles from her home in Clifton.
Finding the vehicle in which Miss Yeates was taken to Longwood Lane, where her body was found covered by snow on Christmas Day, would be a vital breakthrough in the case and Mr Jones made an urgent appeal to taxi drivers and people who attended Christmas functions at nearby golf clubs to contact him if they saw a 4x4 on the night of December 17, when Miss Yeates was last seen alive.
He said there was no evidence that Miss Yeates had been sexually assaulted, though he had not ruled out the possibility “that there might have been a sexual motivation”.
As the investigation entered its third week, Mr Jones admitted that he still did not know where or when Miss Yeates died, whether she disturbed someone who was in her flat when she got home, or whether someone broke in.
He also said he still does not know whether Miss Yeates had eaten a pizza which she had bought on her way home on the night she was last seen. No trace of the pizza or its packaging has been found, suggesting Miss Yeates could have stopped at someone’s house on her way home and eaten it there.
Police are sifting through 293 tonnes of rubbish seized from bins near Miss Yeates’s home in the hope of finding the packaging, which could have the killer’s fingerprints on it.
As he defended what he described as a “painstaking investigation”, Mr Jones added that more than 1,300 pieces of information have been logged, generating more than 900 lines of enquiry, of which 239 are being treated as high priority.
He also said officers had viewed more than 100 hours of CCTV footage in their search for an image of the killer or their car, with further footage still to be analysed.
Miss Yeates had spent the evening of Friday, December 17 with friends at the Ram Pub in Park Street, Bristol, after her live-in boyfriend, Greg Reardon, 27, travelled to Sheffield to visit his half brother for the weekend.
Mr Jones said he was “satisfied” she returned to her flat that night, but what happened next remains a mystery, as her coat, keys and purse were all left behind when she disappeared.
Before his was arrest last Thursday, Mr Jefferies told police he had seen his tenant outside the flat with two other people that night, though he later gave a conflicting account of what he had said. He was questioned by police for three days before being released on police bail on Saturday.