Detectives investigating the disappearance of Nicola Bulley made a mistake by declaring too “early” that she was in the River Wyre, a diving and forensics expert involved in the case has claimed. Peter Faulding, whose Specialist Internationalist Group firm searched a stretch of the river where Bulley was last seen, said Lancashire constabulary should initially have kept other lines of inquiry open for longer, as the search for the missing mother-of-two entered its 16th day. Bulley, 45, of Inskip, Lancashire, disappeared while walking her dog in a field next to the river in St Michaels on Wyre on 27 January after dropping her two children off at school. Faulding, who has worked on a series of high-profile missing person cases – including MI6 officer Gareth Williams who was found naked inside a padlocked bag – cast fresh doubt on the theory that Bulley had fallen into the river in an interview with the Daily Mail. “I think the worst mistake the police have made was to declare early on that she’s in the river rather than saying ‘let’s keep lines of inquiry open’,” he said. “This is a lady who knew this area intimately, she was slim and fit, and if she had fallen, she could have grabbed on to the bank.” Faulding suggested that a third party could be involved, and that Bulley’s phone could have been placed on the bench to act as a “decoy”. On Friday, her partner, Paul Ansell, said he was “100% convinced” she was not in the river, and suggested that somebody “who knows the local area” might be involved in her disappearance. In an interview with Channel 5, Ansell explained that he and his partner had done the walk where she disappeared for years. He said someone in the village must know something about what happened to the mother of their two daughters. “Whatever has happened – in my eyes – has to be somebody who, who knows the local area, who knows that. And the fact that nothing’s been seen or heard, I just truly believe that it’s something in the village,” he said. “It is horrendous because … people don’t just vanish into thin air. It’s absolutely impossible. So something has happened. “My plea now is personally, I want every house, every garage, every out building, the land scrutinised. I want it all searched. I want it all scrutinised, every piece of it. And I’m, you’re not gonna appease me with anything else. That, that is what I want to happen.” Louise Cunningham, Bulley’s sister, publicly doubted the police’s assumption that she had fallen into the river. She wrote on Facebook: “Off the back of the latest police media update, please can I add there is no evidence whatsoever that she has gone into the river, it’s just a theory.” Heather Gibbons, a friend of Bulley’s, told Times Radio on Saturday that her loved ones “cannot accept a theory for conclusion”. She said: “Nikki’s a strong swimmer. She does that walk frequently. She doesn’t generally go near the river on that walk.” Gibbons added: “But then you look at the area, and you can see why it is the police’s working hypothesis. But at the moment, that is exactly what it is … there is no concrete evidence to it at all.” Lancashire police insisted officers were keeping an “open mind” while continuing to appeal for information. They have discounted foul play and are treating the incident as a missing persons inquiry. On Thursday, the focus of their search switched from St Michael’s to about 10 miles downstream where the river empties into the sea at Morecambe Bay, with patrol and rescue boats spotted in the area. Police have repeatedly returned to areas of the river they have previously searched because of tides making the search “particularly complex”, the lead investigator Supt Sally Riley said. In a press conference earlier in the week, she advised members of the public not to take any meaning from these extra searches and urged people “not to take the law into their own hands” or “do anything that would thwart” the investigation. “Based on all the work we have done up to now, our belief remains that Nicola may have fallen into the river for some reason, but we are continuing to investigate all possible leads, and this involves viewing CCTV, dashcam footage and speaking to people who are providing us with information,” the force said. “It remains the case that at the present time, there is absolutely nothing in all the extensive inquiries we have made that suggests anything untoward has happened or that there is any third-party involvement in Nicola’s disappearance, but the investigation is ongoing.”