A letter making reference to murder victim Joanna Yeates and containing a torn-off pizza label was sent to the pub where she enjoyed a final drink with colleagues, it has emerged.
The note, which was scrawled in A5 paper in black ink, was sent to the Bristol Ram pub shortly after her body was discovered on Christmas Day.
Written on lined paper ripped from a notepad, the letter included a fake address and telephone number, and mentioned Miss Yeates by name.
It also contained a label torn from a pizza box, and made reference to various pizza toppings.
Miss Yeates, who disappeared on December 17, had bought a mozzarella and tomato pizza on her way home from the Bristol Ram. But no trace of it or its packaging has ever been found.
Detectives hunting the killer of the 25-year-old landscape architect have seized the letter and label as part of their investigation.
It is understood the letter did not make direct reference to the murder of Miss Yeates but police are still keen to trace the sender.
The landlord of the Bristol Ram, Alex Major, confirmed the information was correct but said police had requested he does not speak about the matter.
A source said: "I was in the pub when the police came but saw the letter before they took it away.
"As soon as I saw her name I realised it could be very important. The police were clearly interested.
"I could not see whether the label came from the same pizza that she is supposed to have bought."
Miss Yeates went to the Bristol Ram on Park Street on the evening of December 17.
She then walked back to her rented flat in Canynge Road, Clifton, stopping off at a Waitrose store, a Bargain Booze shop and a Tesco Express on her way home.
She was reported missing by boyfriend Greg Reardon, 27, two days later when he returned home from a weekend away.
Her snow-covered body was found three miles away at the side of Longwood Lane in Failand on Christmas Day.
Miss Yeates' landlord Chris Jefferies, 65, a former teacher at Clifton College, was arrested on suspicion of murder on December 30 but released on police bail two days later.
Last Friday police retraced her final movements, speaking to more than 200 people in Failand, Clifton and at the Bristol Ram in Park Street.
Leading criminologist Professor David Wilson said he was not surprised the letter had been sent.
He said: "I am inundated with letters about Joanna Yeates on almost a daily basis.
He added: "Her story connects with people who read newspapers, watch television or listen to the radio.
"When a story connects with a lot of people they want to be associated with it. That letter arrived at the Bristol Ram just because it is involved in the case.”
A spokesman for Avon and Somerset Police said all reports linked with the murder case were taken seriously.