A teenager who has been missing for two months may have been “angry, upset and crying” on the day she was last seen.
Leah Croucher, 19, disappeared while walking to work on Buzzacott Lane, Furzton, Milton Keynes, at about 08:15 GMT on 15 February.
Thames Valley Police said three people had reported possible sightings of Ms Croucher near Furzton Lake between 09:30 and 11:15 on that day.
All three said they believe they saw the woman on her phone.
The first witness reported seeing a woman typing on her mobile by the lake between 09:30 and 10:00.
Two other witnesses, who were walking together, described seeing a female who was visibly angry, upset and crying between 10:00 and 10:15.
About 20 minutes later they saw the female again and said she was in a calmer state and possibly speaking to someone on her mobile phone.
Ch Insp Neil Kentish said: “We are very eager to establish the identity of the person who was described to us by the three witnesses.
“Even if this person was not Leah, we would still like to speak to them so that we can eliminate the sightings from our inquiries.”
Mr Kentish described the investigation into Leah’s disappearance as “extensive”, with officers visiting 4,000 homes and speaking to 100 potential witnesses.
The force has worked with the major crime unit, family liaison officers, search teams, the mounted section, police dogs, marine specialists, and the national police air service.
Leah’s parents, Claire and John Croucher, said in a statement: “It has now been 62 long and heart-breaking days since our beautiful, wonderful daughter Leah vanished into thin air.
“When Leah was first reported missing we honestly believed that she would be home very soon.
“But that hasn’t happened and as each subsequent day begins we are filled with despair that another night has come and gone and we have received no phone call or visit, meaning that Leah is still missing.”