Police are keen to speak to a dog walker who may have crossed paths with missing Strabane woman Marian O'Neill on Monday morning at approximately 10am.
Police say that would have occurred along the bottom of a field which would be adjacent to the Strabane Golf Course which runs along side the river.
Marian would have been walking in the direction of Sion Mills and the dog walker towards Strabane.
The 55 year old, was wearing a red jacket, dark trousers and white shoes when last seen on Monday morning.
Police are growing increasingly concerned for Marians welfare and are appealing to the dog walker in question or anyone who was in the area on Monday morning and who may have information to contact them.