56-year-old Michael, who also goes by Mike, was reported missing from his home near Kenmare on Friday, after being last seen in the town day before.
Gardaí have released information and a CCTV image of Michael Gaine from the last known sighting of him.
He bought phone credit in Centra in Kenmare at 9.48am on Thursday.
Hundreds of people have helped in searches for Mr Gaine, who is a very popular figure in the local community.
Searches have been continuing throughout the past few days with gardaí, Kerry Civil Defence, Iveragh Coast Guard, Kerry Mountain Resue and the R115 rescue helicopter all proving assistance.
Parish priest in Kenmare Fr George Hayes says the whole community is praying for Michael.
The search is continuing today and Gardaí say they are particularly interested in speaking to people with CCTV or dash-cam from last Thursday or Friday.
Michael is described as being approximately 5 feet 10 inches tall with a stocky build, brown/grey hair and a bushy beard.
When last seen, Michael was wearing an orange woolly hat, black fleece, blue jeans and black boots.
Anyone with information on Michael's whereabouts is asked to contact Killarney Garda Station on 064 667 1160, the Garda Confidential Line at 1800 666 111, or any Garda Station.