Police investigating the murder of Leah Croucher have issued an image of what they believe her suspected killer looked like when she disappeared.
The 19-year-old's remains were found in a property in Loxbeare Drive, Furzton, Milton Keynes in October, more than three years after she went missing.
Neil Maxwell, who was found dead in April 2019, remains the only suspect.
Detectives believe Maxwell changed his appearance to evade arrest for another crime.
Ms Croucher was last seen walking to work on 15 February 2019. Her cause of death is "still under investigation", an inquest heard
At the time Ms Croucher went missing, Maxwell was on the run from police in connection with a sexual assault in Newport Pagnell in November 2018, and he had previous convictions for sexual offences against women and children.
Thames Valley Police said the 49-year-old, who worked as a maintenance man for the owner of the Loxbeare Drive home owner, who lives abroad, was the only person to have keys to the house.
Officers also found Ms Croucher's rucksack and other possessions in the loft of the house
in Furzton in October.
Police believe Maxwell changed his appearance to evade arrest as no witnesses have placed him in Milton Keynes since December 2018.
The force has now released an e-fit image of what they believe Maxwell may have looked like between December 2018 and April 2019.
Giving an update on the investigation, Det Ch Supt Ian Hunter said the "complex investigation" had "made steady progress" with hundreds of people interviewed and extensive forensic searches and examinations taking place, as well as CCTV reviews.
He said: "Despite the comprehensive media reporting along with the further enquiries with acquaintances, associates and employers and the new house to house and CCTV inquiries, we have still not identified anyone who saw Maxwell in or around Milton Keynes since early December 2018.
"More pertinently we are yet to identify anyone who had seen Maxwell in Loxbeare Drive before, after, or at any time close to when Leah went missing on 15 Feb 2019."
Police believe he also used false names and stopped using his mobile phone and known vehicles.
Officers are appealing for people to come forward with information about Maxwell's movements and identity based on the new image.
"He is likely to have known he was returning to prison if he was arrested and convicted," Det Ch Supt Hunter said.
"The investigation has now also established that Maxwell is likely to have changed his appearance to avoid being recognised. He had grown a beard and may have lost weight."
He said the force was "absolutely committed to establishing the truth" and Ms Croucher's family are "at the heart of everything we do".
Police say Neil Maxwell may have changed his appearance to evade arrest for a sexual assault.