Four years have passed since Cian Langelaan was last seen.
The 27-year-old was last spotted in Hornhead on Sunday, September 27, 2020.
At the time, he was reported missing from the Falcarragh area.
Gardaí say Cian is 5 feet 8 inches tall and of medium build, with sandy-coloured hair.
He was wearing blue jeans, a white t-shirt, and black boots.
They are appealing to anyone who believes they have information that could assist investigations to contact Milford Garda Station.
