Police investigating the murder of Jo Yeates are now wondering if she was strangled wth her own sock or grabbed by her killer, or killers, as she went to collect Christmas cards from her letterbox.

The building she lived in had a communal postbox and she would have had to travel down a dark pathway to get her mail.

While it is pure speculation, it might explain why no forced entry to her flat was apparent and why her coat and shoes were left behind.

A 39-year-old man who used to live in the building told the Daily Mirror: “Jo could easily have popped out to get her post that night and I told the police this theory. My wife and I used to do it all the time at all times of day and night.

“The post room wasn’t very far, so sometimes I’d run out in my slippers or even socks.

“If someone was hanging around they could have grabbed her, it’s very dark. Alternatively, in the time it took Jo to leave her flat to reach the communal area, a prowler could have sneaked in her unlocked flat and laid in wait.”

There’s no doubt police will investigate the theory as they continue the battle to solve the murder but yesterday the focus was on one of Yeates’ socks.

The man in charge of the investigation, Detective Chief Inspector Phil Jones, said the 25-year-old landscape architect was wearing only one sock when her body was discovered. Police considered this an important part of the the crime.

“We are keeping an open mind about whether the sock was used to strangle her,” Jones said.

“We are also keeping an open mind about whether it is being used as a trophy.

“The sock could be in the possession of the offender or in a house or a vehicle.”

Until yesterday, police had only revealed that Yeates was “fully clothed” when her body was discovered near the edge of a quarry about three miles from her Bristol home.

The new revelations suggest that she arrived home and took off her boots and coat, before either opening the door to her killer or disturbing him in the flat.

Jones refused to reveal if anything else was missing from Yeates’ flat.