The family of missing Tyrone retired librarian Mrs Attracta Harron (65), who has not been seen since she went to Mass last Thursday, are appealing to the public for assistance in finding her.
Mrs Harron, a mother of five, crossed the Border into Donegal at 9.30 a.m. on Thursday morning, to attend Mass in Lifford.
She was seen later at around 10.30 a.m. but since then no trace of her has been found.
The PSNI sub-aqua team along with the Foyle rescue crew are searching all the local waterways in the North, while in the southern side of the Border the Garda air support unit are also searching.
Mr Michael Harron said his mother was fit and well before she disappeared.
"She is well known in Strabane. She has an active life and would walk four to five miles per day. This is completely out of character for her."
Mrs Harron is described as five feet tall and has grey-blonde hair set in a bob. When last seen she was wearing a red duffle coat and black trousers, and was carrying a brown handbag.
A yacht and its German crew were being towed to safety last night after getting into difficulty off the Co Donegal coast.
The yacht was being brought to Greencastle by a local trawler, the Naomh Eoin, according to the coastguard service.
Two coastguard helicopters and the Portrush lifeboat went to assist the yacht after a mayday call was received shortly before 12 a.m. yesterday.
The boat, which was believed to be taking in water, was located about 30 miles north of Tory Island.
Weather conditions in the area were severe, according to the coastguard, with gale-force winds.