Middlesbrough teenager Donna Keogh disappeared 20 years ago and Cleveland police now believe she was murdered.
Her body has never been found.
Officers are excavating an area of wasteland three miles from where the 17-year-old lived with her cousins in a flat block close to the town centre.
The waste ground, which is surrounded by houses, was once divided up into plots for people to grow fruit and vegetables.
The investigation had previously been focused on three areas of the town; Aske Road, Bow Street and Hartington Road.
Reports suggested Donna was last seen around Hartington Road in April 1998.
Cleveland Police announced on Monday that they and a specialist search team had started excavation work on the new site in Saltersgill, to the south of Middlesbrough, in a bid to find fresh information.
Detective Superintendent Michael Hunt said the force’s investigation had helped identify several areas where it will carry out “targeted searches in an attempt to find Donna and discover what happened to her in 1998”.
Mr Hunt added: “Donna’s family desperately want to give her a proper funeral and finally lay her body to rest. Finding Donna continues to be a priority for the investigation team.”
Police said that there was no set timetable for the excavation.
The disappearance of Donna is one of three cases being re-investigated after the Cleveland force was awarded £3.77 million by the Home Office in 2017.
Two other young women disappeared in Middlesbrough between 1998 and 2002.
Vicky Glass, from the Roseworth area of Stockton, disappeared in September 2000. In November that year the 20-year-old’s body was discovered at Danby, North Yorkshire.
Rachel Wilson went missing from Deal Court, Middlesbrough, in June 2002. In 2012, her skeleton was discovered in a ditch on the entrance track to Newham Hall Farm, Middlesbrough.
No one has ever been convicted for any of the suspected murders.