Jo Yeates's parents say killer must not be shielded
The parents of Jo Yeates have urged anyone shielding her killer to come forward.
David and Teresa Yeates said holding back information was prolonging the family's torment and could allow the killer to strike again.
Mrs Yeates, of Ampfield, Hants, said anyone noticing unusual behaviour in a friend or relative should tell police.
The body of 25-year-old Miss Yeates was found near Bristol on Christmas Day, eight days after she went missing.
Making an appeal at a Bristol hotel, Mr Yeates, 63, and his wife, 58, asked people to consider whether anyone they knew had surprised them with their reaction to the murder.
They said: "It would appear the nation is shocked and appalled by what has happened to our daughter.
"Do you know someone who has been, somehow, justifying her being killed?"
Miss Yeates's snow-covered body was found in Longwood Lane in Failand by dog walkers on Christmas Day.
Her parents said they spent much of their time wondering how their daughter could have ended up dead by the side of a country lane.
The couple said they were confident justice would be done but they also urged what they called "armchair detectives" to offer any relevant information to the police.
Mr and Mrs Yeates asked the public to report friends or relatives whose behaviour had been unusual - or inexplicable - since Miss Yeates disappeared.
They said: "Do you know anyone that hasn't been shocked or disturbed (by the case)? Has anyone you know had an unusual or inexplicable reaction?
"Was their behaviour unusual on the weekend of 17/18/19 December, or throughout the past three weeks?
"Do you know someone who has been behaving out of character either by actions, or what is said - or not said? Do you know someone who has inexplicably become reclusive, quiet or vocal?"
Mr and Mrs Yeates were joined by their son Chris, 28, and their daughter's boyfriend Greg Reardon, 27, as they read their statement.
Miss Yeates, who grew up in Ampfield in Hampshire and worked as a landscape architect, was last seen alive on 17 December.
She spent the evening in the Bristol Ram pub with colleagues before visiting a nearby Tesco Express to buy a pizza on her way home to the Clifton area of Bristol.
She was reported missing by Mr Reardon two days later after he returned from a weekend away to the flat where they lived in Canynge Road, Clifton, but she was not seen again before her body was found on Christmas Day.