The operation was launched after the man rang his wife early yesterday morning and suggested he intended to cause himself harm.
His car was later recovered at the end of the south pier at Wicklow and a jacket, identified as his, recovered.
Gardaí rushed to the scene after they received a call from the man’s wife, who had recently separated from him, and a full-scale search operation was put in place.
The RNLI, which has a base at Wicklow harbour, launched a lifeboat at 11.30am. The Garda sub-aqua team arrived just before 1pm, while the Coastguard helicopter arrived at around 4.40pm.
The search was called off at 5pm as darkness fell and will resume will this morning. Garda sources said there can be strong currents in the harbour.
Meanwhile, questions were being asked last night as to how the man was able to move freely given the danger he posed to himself and his children.
He was arrested at 1pm on Wednesday after he crashed his car at a roundabout near his home in Rathnew, Wicklow, following a Garda pursuit. The man’s three daughters — aged 12, nine and seven — were not injured.
Gardaí took the man to Wicklow Garda Station and detained him under the Mental Health Act pending his assessment by a doctor. Following this he agreed to voluntarily admit himself to a psychiatric hospital.
He subsequently left the hospital and never returned.
Medical sources told the Irish Examiner there were three possible scenarios explaining how the man was able to leave hospital:
* He left without the knowledge or permission of staff.
* He insisted on leaving and was discharged contrary to medical advice and/or staff believed they could not meet the threshold allowing them to detain him involuntarily.
* The man wanted to leave and staff agreed to a planned discharge, with an arrangement to see him on another occasion.
Medical sources said that given the man was willing to admit himself voluntarily into hospital, it would have been difficult and legally questionable for the doctor at the Garda station to have detained him involuntary.
Garda sources said officers went to talk to him on Thursday evening after it emerged he had not returned to hospital.
“We said it was important for him go back in for treatment,” said one source. “We tried to get him to return. There’s nothing more we could have done.”
A spokeswoman for the HSE said they did not comment on ongoing investigations.