Detectives investigating the disappearance of RAF serviceman Corrie McKeague insisted finding the 23-year-old is as a priority for the force.
Suffolk Constabulary spoke out amid criticism that not enough is being done by them to find the 23-year-old gunner, whose family has spearheaded an intense media campaign.
Officers described the case as an “active and continuing investigation” despite being no closer to finding Corrie four months after he vanished.
A spokesman for the force said: “As long as we still have lines of enquiry to follow, as we do now, this will remain an active and continuing investigation.
“Police still have work to carry out around a number of aspects of the investigation and we continue to treat finding Corrie as a priority for the Constabulary.”
Earlier this week, Corrie’s mother Nicola Urquhart admitted the chances of finding him alive are diminishing.
She was joined by a 100-strong team of volunteers and four Cadaver search dogs, specially trained to seek out corpses, to scour an area close to Bury St Edmunds, Suffolk, where Corrie was last seen on September 24.
Speaking during the search, Nicola said: “In my head, I believe Corrie is still alive, that he could still come home, but as soon as I go out looking, I know that’s not what I’m looking for.
“It’s really confusing in my head and it has been very emotional.
“It was difficult to deal with but I’ve got to look for him. I’ve got to try and find him.”
Nicola and her family previously publicly criticised Suffolk Police for not doing enough to trace missing Corrie.
They hired an “elite team of specialists” after raising more than £50,000 to task private investigators to help with the search.
Suffolk Constabulary insisted they have carried out “extensive” investigative work, scouring hundreds of hours of CCTV and tracing dozens of people who may have held information.
They explained why the rubbish site which could have contained Corrie’s phone was not searched after it gave off a signal around 13 miles away in Barton Mills, Suffolk.
A spokesman for the force said: “We needed to focus on investigating and searching the areas where we were most likely to find Corrie, with searches and CCTV prioritised as lines of enquiry.
“Analysis of Corrie’s phone showed it had moved between Bury St Edmunds and Barton Mills around an hour after the last confirmed sighting of Corrie.
“There was then no further signal from the phone.
“Police used the CCTV available outside of the Bury St Edmunds area to see if the movement matched with any vehicle movement and found that the bin lorry had travelled between the two locations at the time, however it cannot be ruled out that another vehicle also made the journey.
“Officers have looked at the possibility that the phone may have been inside or on the bin lorry in some detail but this cannot be confirmed - and there is nothing to indicate whether the phone fell off the vehicle at Barton Mills, was crushed within the vehicle or stopped giving out a signal for another reason.
“Extensive work is still underway in connection with this, including enquiries to gather the information that the phone may have been able to provide.”
The force explained that much of the information that would be available if they had possession of Corrie’s mobile phone has already been established.
However, the spokesman added: “There is a possibility there is information on the phone that is not available to the investigation, however the value of this cannot be ascertained.”
Suffolk Constabulary also addressed whether they were aware of all the details of Corrie’s social media accounts, including the recent swinger website which was reported last week.
A spokesman said: “Police were aware of the social media sites and websites Corrie was using from the first few days of the investigation and work has been carried out around this as part of the enquiry.”
They also once again ruled out any link with an attempted abduction of an airman at RAF Marham, Norfolk.
Following the fresh comments, Corrie’s mother Nicola Urquhart, 48, said: “Anything I would want to say just now would be really positive to the police.
“I was perhaps disappointed I had to go to the lengths I did to get some of the actions carried out, but I’m absolutely delighted that they have.”
Anyone with information over Corrie’s disappearance should call Suffolk police’s incident room on 01473 782019.