Joanna Yeates was strangled several days before body found, detectives reveal

The 25-year-old, whose body was found on a grass verge on Christmas morning, died as a result of "compression of the neck".

Detective Chief Inspector Phil Jones, who is leading the investigation, said he believed her body had been dumped in Longwood Lane, Failand, near Bristol, "several days" earlier.

He said a number of lines of inquiry were being pursued, including the possibility that there was a sexual motive behind her death or that the graduate knew her killer.

Police are also keeping an "open mind" over whether Miss Yeates had been held captive or killed where she was found.

Miss Yeates' father yesterday said he was "relieved" to be reunited with her body and he is now hoping her killer will be brought to justice.

David Yeates, 63, said: "I fear that whoever has done this will never hand themselves in, but we live in hope that the police will catch who is responsible.

"We are sure the police know more about what happened than they are telling us, but at the moment we are not questioning them because we feel they are doing their best."

Miss Yeates' boyfriend, Greg Reardon, 27, who reported her missing on the night of Sunday, 19 December, after returning home from a weekend away in Sheffield visiting family, is being treated as a witness and not as a suspect, according to Mr Jones.

He said: "The investigation into the death of 25-year-old Joanna Yeates is now a murder investigation and I am leading that murder investigation.

"As you know the post-mortem examination has taken longer than usual, because of the frozen condition of her body. The pathologist completed his examination last night and concluded the cause of her death was compression of the neck - in other words, strangulation."

She had been missing for eight days when her clothed body was discovered about three miles from her home by a couple walking their dogs. Forensic officers are still searching the Failand area and Miss Yeates' flat in Canynge Road.

"There are a number of other lines of inquiry that we are pursuing," Mr Jones said. "One of these is inevitably going to be how Joanna got from her home in Clifton to Longwood Lane, which is about three miles away.

"This means that we will be looking at any possible routes that could have been taken to get to and from that location.

"This includes reviewing relevant CCTV footage from cameras on the Clifton Suspension Bridge, which is an obvious link between the locations.However, this is just one of a number of routes that could have been taken, and we need to make sure we cover every possibility."

Miss Yeates was last seen on the evening of 17 December having bought a pizza in Tesco Express in Clifton at about 8:45pm. Police believe she then walked the short distance home to the ground-floor flat she shared with her boyfriend, where her keys, purse and bank cards were found, together with a Tesco receipt.

Earlier that night, she had been drinking with work colleagues at the Ram pub in Park Street. Miss Yeates left there at about 8pm and, while walking to a Waitrose store, phoned her friend Rebecca Scott to arrange to meet on Christmas Eve.

"We also know that she went to the Bargain Booze shop and a Tesco Express store in Regent Street, Clifton, where she bought a pizza, leaving that store at about 8:30pm," Mr Jones said.

"At the time she would have arrived home, which would have been approximately 8:45pm, there were other pedestrians and vehicles in Canynge Road.

"Somebody out there does know what happened to Joanna. Somebody out there is holding that vital piece of information we need to help provide Joanna's family with the answers they need and want."