Family vows to carry on looking for Claudia Lawrence

With no sightings of the missing chef, the number of officers on the case has been scaled down to seven

The police have all but called off the search. In truth, few hold out any hope of seeing Claudia Lawrence alive again. Among those few are her family, who refuse to give in or accept that the 35-year-old chef is dead.

In the hope of rekindling public interest, family members have taken part in a new documentary: Missing – The Claudia Lawrence Story. In the programme, to be broadcast on Channel 4 next week, her sister and father describe how they have struggled to cope in the 16 months since Claudia vanished from her home in York.

Her father, Peter, a regular churchgoer, says his faith has been tested by the ordeal and his "lowest point" was on being told last year that a body had been discovered. "It was back in York, and it was four hours, travelling back on the train, of absolute turmoil before we discovered that it wasn't Claudia," he recalls.

She dominates his every waking moment: "I obviously think about what might be happening and it's something you just do all the time."

Although police are treating the case as one of suspected murder, Mr Lawrence is convinced his daughter is still alive: "I may be proved wrong, but I just feel that I would have felt something different inside me if she'd been killed."

The search for Claudia has been one of the biggest ever investigations by North Yorkshire Police, with a team of 100 officers involved, more than 1,000 witness statements taken; hundreds of houses and large areas of countryside searched; countless posters distributed, appeals broadcast on Crimewatch; and a £10,000 reward for information. Detectives even went to Cyprus in search of new leads.

But from today the number of officers on the case, already reduced to 16, will be cut to seven. With no confirmed sightings and no trace of a body, police have all but shelved the case.

Although the family is careful not to criticise the police publicly, a statement issued by one of Mr Lawrence's friends, who acts as a spokesman for the family, described the scaling down of the investigation as "regrettable".

The lack of any progress is taking its toll. Claudia's sister, Ali Sims, is plagued by nightmares. "It's playing on my mind subconsciously because I dream about someone snatching her or someone beating her – awful images that it's too hard to describe, but they're always her walking in the dark, or walking to work, and something horrible happening to her."

She hits out at the way her sister's love life has been presented in the tabloids. "It's almost like you're not reading about your sister. You're reading about someone else. If Claudia was around to read it, she'd be absolutely mortified."

The missing chef has been portrayed as "a posh call girl" in some speculation over her relationships. "Wrong. Claudia wasn't that," claims one of her childhood friends, Melanie Wright.

The focus on Claudia's personal life has damaged the campaign to find her, claims her long-time friend Suzy Cooper. "I was like, 'There's going to be people who are going to believe everything they've read and they're going to judge her exactly on that, and they're wrong, and they're going to lose interest...' And on Facebook I watched the numbers go down – and I thought, 'No, this isn't fair.'"

But for Mr Lawrence, the single most important thing is to find his daughter. Speaking to the IoS last night, he vowed, "I am absolutely determined to keep up the campaign to find Claudia. It is the most important thing in my life, and I will continue until she is found."