Castlebar optician Mark Deely says there's a possibility his brother Trevor is still alive, after being missing for 21 years.
He's issued a new appeal for information on the Naas man - over two decades after he vanished in Dublin.
Trevor was last seen on CCTV passing the Bank of Ireland ATM on Haddington Road at 4.14am this day 21 years ago.
31 seconds later, a male appears in the footage walking in the same direction as Trevor.
Forty minutes earlier, an unknown male is seen talking to Trevor at the back gate of his workplace in Wilton Terrace, nearby.
Mark says the person in both images has never been identified.
21 years later, Mark believes there is a possibility Trevor is still alive.
A 100,000 euro reward is available for anyone who provides information that helps to solve the case.