Fears were growing last night for the safety of a father of three, who was at the centre of a garda alert earlier this week after he disappeared with his children.
After they had been located, the man was taken to Wicklow garda station and sent for medical treatment.
Following an examination by doctors, he was later deemed fit to be discharged from hospital and returned to his Co Wicklow home.
But concerns about his whereabouts emerged yesterday morning after he left his house and his car was later found parked at the harbour in Wicklow town.
Gardai carried out a search in the area and found a jacket belonging to the man.
Senior officers decided to call in personnel from the force's underwater unit to trawl the harbour at South Quay, while Wicklow lifeboat crew were asked to search the sea around the mouth of the harbour.
A Coast Guard S-61 helicopter also joined the operation with a powerful searchlight, while Coast Guard personnel combed the headland without any success.
The search was called off as darkness fell yesterday evening but officers said it would be resumed this morning.
One officer admitted last night that they were seriously concerned about the safety of the man as he had not been seen since 8.30am and had not been in contact with any of his family or friends since then. Gardai confirmed that the three children were safe.
It was the second time this week that the man had been the subject of a garda search.
On Wednesday, he sparked off an investigation after he collected his children unexpectedly from a national school and drove way.
Some hours later, garda patrol crews saw the car on the N11 exit at the Ballinabarney junction, outside Rathnew.
The driver lost control of the vehicle and ended up on a roundabout.