Michael Deely, whose son Trevor disappeared over 20 years ago, has died.
He had campaigned tirelessly to find his son who was last seen in Dublin in 2000.
Trevor Deely disappeared after attending his work Christmas party.
He was the youngest of four children from Naas, Co Kildare.
Mr Deely was last seen on CCTV passing the Bank of Ireland ATM on Haddington Road in Dublin just after 4am on 8 December 2000.
Despite an extensive garda investigation at the time, and the opening of a new investigation in 2016, no trace of the 22-year-old has ever been found.
His father was took part in multiple appeals for information over the years to try to find his son.
In 2015, he told RTÉ Radio One that the family always had hope.
"The fact that we haven't heard anything negative ... or haven't heard anything unusual from the gardaí, we can still stay positive."
According to his death notice, on RIP.ie, Michael Deely died peacefully surrounded by his family at the TLC Centre, Maynooth, in Co Kildare.
His funeral mass will take place in the Church of Our Lady and St David in Naas tomorrow.
