The father of a teenager missing for almost a month believes he is still alive, and said his family is "incomplete" without him.
David O'Halloran was last seen in the early hours of Friday January 18 after leaving a night out with friends in Stirling.
His father Alan McInnes fought back tears as he appealed for further information on the missing student. He said: "David has been missing for a month and every day we hope that he's found safe. We remain 100% sure he is alive and hope somebody has seen him or knows where he is. He may have injured himself and someone has helped him.
"Too many people have said he is no longer with us but we have to remain focused that he is alive and that for whatever reason he can't come home. We're looking for a person and not a body. We will continue to believe this until we're told otherwise by police."
After a long pause, Mr McInnes added: "David son, if you can see or hear this, please know that we miss you, we love you and we all need you home. Our family is incomplete without you."
The 18-year-old maths student had gone out with friends after finishing work. They had drinks at Stirling University accommodation before heading out into the city.
At around 1am, Mr O'Halloran was asked to leave a nightclub by a worker and got in a taxi to head home, Central Scotland Police said. He got out of the taxi before arriving at his student flat and said he would walk the rest of the way. He was then spotted by various drivers making his way towards Stirling University.
The last sighting police have of him is CCTV footage showing him crossing Henderson Street in nearby Bridge of Allan at around 2.20am. Police have used mountain rescue teams, trained dogs and a helicopter as part of their search and are now focusing on the River Forth and Carron with underwater diving teams.
Superintendent Gordon Dawson said: "It is four weeks tomorrow since David was last seen and we are extremely concerned for him. We have carried out extensive searches using every available resource but there is no trace of him. We are still keen to speak to the driver of a white car, possibly a Skoda, which was seen driving along Henderson Street prior to the last sighting of David.
"A police patrol car drove down the street at 3am and did not see David so we have a 40-minute gap to narrow down and the driver of the white car may have seen David in another location. We don't want to apportion blame on anyone here, this is a university city and young people go out and enjoy themselves and have a drink and make their way home."