Today Detective Constable Donald Peat said the "extensive" search for McLean would continue today.
"Today LandSAR volunteers, Red Cross volunteers, a rescue search dog and police are searching further afield in the town belt," he said.
"They also continue to search Waikari, Helensburgh, Halfway Bush Kaikorai valley and Frasers Gully.
"Police ask residents to check their properties again, particularly in the Halfway Bush area - please check sheds and outbuildings in or around your properties."
McLean was last seen wearing a dark-coloured polar fleece and trousers, a red polo shirt, brown slippers and a black puffer sleeveless jacket.
He is approximately 152cm tall and of very thin build.
Any sightings of Mr McLean should be reported to police immediately on 111.