The Western Health and Social Care Trust is investigating how the records of 17 patients at the Waterside Hospital came to be in a bin bag which was found in the garden of a house in Derry last weekend.
The records contained highly sensitive information about patients aged from 76 to 93.
The bin bag was found by a woman in Rossnagalliagh, and she gave the documents to the Derry News.
Earlier this week, the paper handed the records over to the trust, which has promised a full investigation.
The Information Commissioner has also been informed.
Ciaran O'Neill is editor of the Derry News...........