Police have launched a search and are appealing for public assistance to help locate missing man Nicholas.
The 37-year-old was last seen walking along Flinders Street across Exhibition Street towards Fitzroy Gardens about 1.41am on Sunday, 22 January.
Police and family have concerns for Nicholas, due to his disappearance being out of character.
Nicholas is Caucasian, medium build, about 180cm, brown hair with a short beard.
He was last seen wearing a dark coloured bomber jacket, blue polo top, multi-coloured shorts, black runners, black socks with a yellow stripe and a blue baseball cap.
Police are also investigating whether Nicholas may have travelled interstate to New South Wales or the Northern Territory.
Melbourne detectives and SES will continue the search today at Treasury Gardens.
Anyone who sights Nicholas or has information on his whereabouts is urged to contact Melbourne West Police Station on 8690 4444.
