DETECTIVES leading the investigation into the disappearance of Claudia Lawrence are submitting a file of evidence to the Crown Prosecution Service.

The evidence relates to four men, all from the York area and aged in their fifties, who were arrested in March and April on suspicion of the missing chef's murder. All four men were released from police bail on Thursday, while the CPS considers the case.

Claudia was 35 when she disappeared in 2009. She never arrived for her morning shift at the University of York on March 19, 2009, but had been seen on CCTV and spoken to her parents the previous evening.

An initial investigation into her disappearance soon became a murder inquiry, but despite more than 100 officers working on the case, a £10,000 Crimestoppers reward for information and more than £750,000 spent on the investigation by 2010, no arrests were made.

Operation Essence, a review into the original investigation into Claudia's disappearance began in 2013, and last year the force released a series of new leads and appeals for information. So far, the review has cost North Yorkshire Police around £400,000.

Detective Superintendent Dai Malyn, who is leading Operation Essence, said the force had reviewed a considerable amount of evidence which would be prepared for submission to the CPS, who will assess the information to decide how the case should proceed, and whether any charges can be brought.

Peter Lawrence, Claudia's father, said police had kept him up to date with the investigation, and he would wait to see how the CPS would proceed.

Mr Lawrence said: "They were bound to be released. It won't be news until we hear from the CPS.

"It's always progress, but we're not at an end of the investigation, and the CPS will let us know in some months what will happen."

Joan Lawrence, Claudia's mother, said: "Today's news is absolutely heartbreaking. My thoughts continue and always will be with Claudia.

"We now have to wait to see what the CPS verdict is and I have no idea what the future holds. As ever, I'm thinking of my daughter."