Joanna Yeates: the case of the missing sock

First a pizza. Then a 4x4. Now police are pursuing a new line of inquiry

As the Joanna Yeates murder inquiry entered its ninth day yesterday, the focus switched to a long, grey ski sock that police said the 25-year-old was missing when her body was found.

It was the latest in a series of ostensibly insignificant clues which could help to explain what happened to the landscape architect in the eight days between her disappearance in Bristol on 17 December and the discovery of her frozen corpse on Christmas Day.

Detectives had previously asked for help in tracing a "light-coloured" 4x4 vehicle seen near the country lane in Failand, North Somerset, where Ms Yeates was found by a dog-walker. The dead woman was not wearing a coat or her boots, but they have since been located at her rented flat three miles away in the Bristol suburb of Clifton.

Yesterday's appeal prompted a man to turn up at Ms Yeates's home to hand in a grey sock he had found, but police later confirmed it was not the one they were looking for. Apparently no closer to catching the killer, the Avon and Somerset force made a further request for assistance from the public.

Yesterday, ITV journalists were barred from a police press conference after News At Ten aired a highly critical report about the investigation. The force said it had complained to the broadcasting watchdog, Ofcom, about what it perceived to be "unfair, naïve and irresponsible reporting".

It added: "A live murder investigation has been under way now for just nine days and the media have played an important role in helping us to appeal for witnesses. While we appreciate the support we have received so far from most of the media, we must step in if we feel coverage will hamper the investigation. Our primary aim will always be to secure justice for Joanna."

Meanwhile, officers continued to sift through 293 tonnes of household waste, looking for the pizza that Ms Yeates is known to have bought from a Tesco store on the night she went missing, after drinking with colleagues at a pub.

The evidence

Much comment has been made about the perceived lack of evidence. The frequency of the police appeals suggests that officers are still actively seeking the public's help to turn up new lines of inquiry.

Apart from the missing sock and pizza, detectives need hard, forensic evidence which might tie Ms Yeates to her killer. Officers have been in and out of her flat at Canynge Road since she was found. They have also studied 100 hours of CCTV footage in an attempt to determine her final movements.

Yesterday, the Daily Mirror newspaper printed a grainy photo which was confirmed as the last known sighting of Ms Yeates. Officers said they had seen the film at an "early stage" of the inquiry and, given that there was better quality video available – security tapes of Ms Yeates buying the pizza at Tesco and some cider at Bargain Booze – they had preferred to focus on the clearer images. Examination of CCTV is also being used to establish how her body came to be dumped in Longwood Lane. Officers want to speak to the driver of a 4x4 spotted there on the night the victim went missing.

The theories

Officers have routinely said they are keeping an "open mind" about almost every theory or suggestion of a motive. There is no sign that Ms Yeates was sexually assaulted, but such a motive has not been ruled out.

Detective Chief Inspector Phil Jones, the man leading the case, also refuses to dismiss the possibility that Ms Yeates was killed by more than one person. Earlier this week, he said: "I assure you we are determined to bring Jo's killers to justice." Asked about his use of the word "killers" rather than "killer", he said the plural emphasised that he was keeping an open mind.

Previously, police had said there was no sign of forced entry at the flat, but earlier this week they seemed to suggest that a killer might have forced his way into the property. Mr Jones said: "I am satisfied Jo got back to her flat but I am not going to speculate whether she let someone into the flat, whether someone was already there or whether someone broke into the flat."

Yesterday's appeal for the missing ski sock prompted another theory – that Ms Yeates was strangled with the garment and the killer kept it as a trophy. Again, detectives said they were keeping an "open mind" about this.

Suspects and witnesses

After establishing that Ms Yeates was murdered, police immediately said her boyfriend Greg Reardon was not a suspect but was co-operating as a witness.

Only one arrest has been made. Ms Yeates's landlord Christopher Jefferies, 65, was held for three days and then bailed. He remains a suspect but is said to deny any allegations and is considering suing for wrongful arrest. Officers are also known to have spoken to Mr Jefferies' neighbour Peter Stanley (though not as a suspect). He reportedly told them that he helped Mr Jefferies to jump-start Mr Reardon's car before the latter drove to Sheffield on the weekend that Ms Yeates went missing.