Joanna Yeates detectives resort to Facebook

Detectives investigating the murder of Joanna Yeates have launched a national campaign on Facebook to appeal for witnesses.

Avon and Somerset Police have set up a page on the popular social networking site appealing for help in their search for the landscape architect's killer.

The 25-year-old's snow-covered body was found on Christmas morning by a couple walking their dogs, just three miles from her home in the Clifton area of Bristol.

So far, more than 1,300 pieces of information have been received, with 900 lines of inquiry pursued. A total of 293 tonnes of rubbish have been searched and 100 hours of CCTV footage viewed as 70 police officers hunt for the killer.

Miss Yeates's grieving mother, Theresa, said she still sits in her kitchen waiting for her daughter to return.

Speaking at her home in Ampfield, near Romsey, Hampshire, Mrs Yeates, 58, said: "She just had this joy and vibrancy, even though she didn't live here. I am sat in the kitchen just wanting her to come through the door. It is just so quiet here without her."

The extensive investigation continued to focus on Miss Yeates's flat, which she shared with her boyfriend, Greg Reardon, 27, as police struggle to confirm key details, such as the exact time and location of her death.

Yesterday, Detective Chief Inspector Phil Jones, who is leading the murder investigation, said: "The majority of people these days are spending time on Facebook and other social networking sites.

"This advert allows us to point people to special features on our website with all the latest information. It allows them to contact the incident room direct online rather than calling in."

Meanwhile, crime scene investigations continued at Miss Yeates's flat yesterday, using advanced forensic techniques to examine the scene. A sign outside the building warned, "Do not enter, dangerous chemicals".

Investigators wearing white suits came out of Miss Yeates's flat, while a number of uniformed officers entered the flat of her landlord, Chris Jefferies, on the opposite side of the building. He was arrested on suspicion of her murder on 23 December but released on bail after two days of questioning.

On Monday, police said they were not ruling out a sexual motive for Miss Yeates' murder, while also suggesting that more than one person may be responsible.

Detectives appealed for help in tracing a 4x4 vehicle seen near the spot where her body was discovered in Longwood Lane, Failand, North Somerset.However, they also revealed that they still do not know when and where she died.

Mr Jones revealed that there were still significant gaps regarding Miss Yeates's final hours.

He said: "I am satisfied that Jo got back to her flat but I'm not able to speculate whether she let somebody into the flat, whether somebody was already in there or whether someone broke into the flat.

"At this time, I cannot say where or when Jo was killed, or when her body was left on Longwood Lane."