15-year-old Arlene Arkinson disappeared after a night out in Donegal in 1994.
Arlene's sister – Kathleen – has thanked a local farmer who reported a piece of disturbed land to police.
The PSNI along with the Arkinson family are appealing for anyone with further information to come forward.
Noel Doherty, whose farm is on the piece of land being searched, explains what he came across when he contacted police.
