London (CNN) -- A murderer is at large in England, police warned in connection with a case that has gripped the country for more than two weeks.
Joanna Yeates, 25, disappeared on December 17 in the city of Bristol in western England. Her body was found on Christmas Day by a couple walking their dogs a few miles from where she lived, police said.
Her parents said the discovery of the body was a relief, but the confirmation she had been murdered "only intensified our grief.
"She was a beautiful and talented young lady who was destined to fly high. Her life was stolen from her and she was stolen from us," they said in a statement on New Year's Day.
Her boyfriend, Greg Reardon, said he would always love her and hoped "for her sake, justice is found swiftly."
Yeates had been out with friends on the day she vanished, and was last seen alive buying a pizza at 8:40 p.m. that Friday night. Reardon alerted the police when he got home to their apartment December 19 after a weekend away.
Her keys, purse and bank cards were in the apartment, along with a receipt for the pizza.
The investigation became a murder inquiry on December 28 after an autopsy concluded that Yeates had been strangled.
A 65-year-old man was arrested on December 30. British media identified him as Yeates' landlord. He was released on bail January 1.
Bristol police have more than 70 officers and staff working on the case, Detective Chief Inspector Phil Jones said the day the man was released.
Chief Superintendent Jon Stratford said Sunday that "whoever killed Jo remains at large," and said people should take "the usual safety precautions.
"Lone women should avoid walking home alone after dark and householders should keep their premises secure and take care answering the door to strangers," he said, adding that there was "no specific intelligence or information to suggest there is an increased threat to their safety at this time."
Police have released CCTV footage from a liquor store where Yeates shopped before buying the pizza.