Christopher Halliwell's daughter in plea for murder truth
Killer taxi driver Christopher Halliwell has been urged by his daughter to "tell the truth" over the death of Becky Godden.
Natasha Halliwell said her father, who is serving a life sentence for the murder of Sian O'Callaghan, should "do the right thing".
Christopher Halliwell, 48, escaped charges over Ms Godden's death because police ignored arrest guidelines.
"He needs to give the other family closure", she told ITV's Daybreak.
In a statement, Halliwell's wife Lisa also said her thoughts were "constantly" with Miss O'Callaghan and Miss Godden's families.
She said she hoped Ms Godden's family got "the justice they deserve".
"No parent should ever have to go through the pain and agony of not ever knowing what happened to their daughter," she said.
Halliwell, 48, admitted to a senior detective that he murdered Miss O'Callaghan and Miss Godden, and even led officers to their bodies.
A judge ruled confessions made on the day of his arrest were inadmissible because Det Supt Steve Fulcher breached police guidelines governing the interviewing of suspects.
The detective, who was leading the hunt for Miss O'Callaghan, failed to caution Halliwell and denied him a solicitor.
Mrs Justice Cox said Det Supt Fulcher's decision to ignore guidelines in the Police and Criminal Evidence Act were "significant and substantial".
'I pity him'
Natasha Halliwell said she had been sent letters by her father but had not replied to them.
"We have had quite a few letters that have said 'Sorry for putting you all through this' and things like this," she said.
"As much as I want to hate him, I can't. I pity him and I do feel sorry for him and I hate what he has done but I can't hate him."
Ms O'Callaghan went missing after a night out in the Old Town area of Swindon in March 2011.
After leaving Suju nightclub, Miss O'Callaghan walked past the Goddard Arms on High Street and got into Halliwell's taxi.
He drove his victim to Savernake Forest, near Marlborough in Wiltshire, where he killed her. He later dumped her body close to the Uffington White Horse in Oxfordshire.
Following his arrest in Swindon, Halliwell led detectives to where her body was left but crucially was not read his rights.
He then took detectives to a field in Eastleach, Gloucestershire, where the remains of Becky Godden were found.
Det Supt Fulcher has been suspended pending an investigation into allegations of "inappropriate contact with the media".
An investigation by the Independent Police Complaints Commission is due to be carried out.