The ‹detective leading the hunt for the murderer of Bristol landscape architect Joanna Yeates has appealed for the public's help.

Detective Chief Inspector Phil Jones has urged anyone with information that could help track down her killer to come forward.

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

He made his plea after disclosing the result of a post-mortem examination which revealed the 25-year-old from Clifton was strangled.

Around 70 police and civilian staff are involved in the investigation, which has become one of the biggest in Bristol for years.

The family of Miss Yeates said yesterday that it had been a "relief" to see her body after going through the worst week of their lives when she was found to be missing.

Her father David, 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 that 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.

"Hearing Jo had been murdered was not a surprise because we had been told to prepare for the worst.

"Since hearing about her death all sorts of things have been running through our mind and we are trying to rationalise what has happened.

"Last week was the worst of our lives and we are hoping that we will never have to go through anything like this again.

"Things were made just that little bit less terrible when we saw Jo's body.

"It was a relief to see her body again – we just said 'welcome back'."

Mr Yeates said his family were keen to make arrangements for his daughter's funeral but they had been informed by the police that her body was unlikely to be released "for a while".

Miss Yeates was last seen alive on December 17 and reported missing by her boyfriend Greg Reardon, 27, two days later when he returned home from a weekend away.

Her fully clothed body was discovered by dog walkers, partially covered by leaves and snow, on a quiet lane three miles from her home, at around 9am on Christmas Day.

The post-mortem examination had been delayed because of the frozen state of her body.

DCI Jones said police believed Miss Yeates' body had lain there several days.

He said: "The pathologist concluded that the cause of her death was compression of the neck; in other words, strangulation.

"As a result of the findings of the post mortem, we believe that Joanna's body has been in the roadside verge off Longwood Lane, Failand, for several days before being discovered on Christmas morning."

DCI Jones said officers were continuing their meticulous search of the area in which Miss Yeates was found in the hope of finding anything that might lead them to her killer.

He said one important line of inquiry was examining all possible routes between her home and the destination where her body was found three miles away.

This investigation will include reviewing relevant CCTV footage from cameras on the Clifton Suspension Bridge, which is an obvious link between the locations.

DCI Jones said he was keeping an 'open mind' about whether Miss Yeates was held before she was killed, whether she knew her killer or whether there was a link to any outstanding missing person or murder inquiry. He said forensic investigations were continuing into information on her computer and mobile phone.

DCI Jones did confirm that Miss Yeates' body had no other significant injuries and that officers were trying to ascertain whether she was killed at the spot her body was discovered.

He declined to speculate on the identity or existence of any suspects but stressed Mr Reardon was a witness and not a suspect.

DCI Jones urged any members of the public to come forward if they have any information whatsoever, however small or insignificant they may think it is.

He said: "We know some of her last movements on Friday, December 17. We know where and when she was found. We now know how she died.

"What we have to do next is find out why she was killed and who was responsible.

"I have a large team of police officers and staff who have been working tirelessly to help find the answers to those questions.

"I would urge anyone listening who has any information whatsoever to please come forward and speak to us."

Miss Yeates, a landscape architect for city-based firm BDP, was reported missing on the evening of December 19 by Mr Reardon.

He had returned to the couple's home in Canynge Road, Clifton, after a weekend away in Sheffield visiting family.

Miss Yeates was last seen alive two days earlier after visiting the Bristol Ram pub on Park Street with work colleagues.

She left the pub at 8pm and stopped on her way home at Waitrose on Clifton Triangle.

At 8.30pm she rang her best friend, Rebecca Scott, to arrange to meet on Christmas Eve, and at 8.40pm she left the Tesco Express on Regent Street in Clifton, where she had bought a Tesco Finest mozzarella, tomato and basil pesto pizza.

It emerged yesterday that Miss Yeates also bought a bottle of cider at off licence Bargain Booze, also in Regent Street.

Shop assistant Robin Paine, 54, said: "It was a really busy night because it was the last Friday that the students were here. I don't remember her coming in but she is on our CCTV, which the police took on Monday morning.

"That was less than 24 hours after she had been found so it made me think something awful had happened to her.

"It's hit the community very hard – it's all anyone is talking about.

"It's quite horrifying to think that this can happen and that it now appears she's been murdered. We all feel for the family, especially given the time of year."

What happened before Mr Reardon returned to the couple's flat on Sunday evening, after visiting his brother in Sheffield, is unclear.

He found Miss Yeates gone but her coat, mobile phone, keys, purse and bank cards still in the flat.

The pizza and its box were missing, and police have since appealed for information as to its whereabouts.

Police have said there were no signs of forced entry or a struggle at the Victorian flat, which is near Clifton College.

Eight days later Miss Yeates' body was found close to the entrance of Bristol and Clifton Golf Club, in Failand.

Bob Cook, district councillor for Long Ashton and Failand, said yesterday: "It is dreadful and has been very upsetting for the people of both communities in Failand and Long Ashton.

"We never expect this sort of thing to happen where we live.

"It is very sad as it affects so many people and our hearts go out to her family and friends."

Miss Yeates' body was formally identified by her parents David and Theresa on Monday.

Together with their son, Christopher, and Mr Reardon they made an emotional visit to the site where she was discovered.

After laying flowers nearby they made their way to Flax Bourton mortuary to formally identify her body.

Anyone who can help with the investigation should call the Operation Braid incident room on 0845 456 7000 or Crimestoppers, anonymously, on 0800 555111.