Forensic scientists at Dundee University were called in to assist the investigation after the badly decomposed remains were discovered in Rusheen Woods near Barna on the edge of Galway city last September.
DNA samples have been circulated to databases in Ireland, the UK, the US and across Europe without a breakthrough.
The dead man was Caucasian and believed to be aged 30 to 40 while dental examinations have revealed he had a distinctive gap between two front teeth.
Gardaí believe the man had a connection with the US, based on some of the clothes he was wearing, including white and blue Athletech runners which are commonly sold in major American department stores.
The man was about 1.8m tall with black hair and of broad or strong build, detectives said. He was also wearing a gold bracelet watch, Caravelle by Bulova, and had a black leather jacket, blue jeans and black belt with metal flower design studs across its length with a silver-coloured buckle. The man also had small amounts of sterling and euro in his pockets when found.
The spot where his body was discovered was about 6m into the woods and the area, which is popular with birdwatchers, would commonly be accessed from close to a nearby windsurf school or at low tide by walking from Silverstrand beach.
The man’s death is not being treated as suspicious.
Due to eight weeks of fine weather last summer before the discovery was made, detectives said the body was in an advanced stage of decomposition and may have lain undisturbed for up to eight weeks.
Detective Sergeant Paudie O’Shea appealed for anyone who thinks they saw a man fitting the description in the area last summer, or for people who let accommodation in the area and may have been in contact with him, to get in touch.
“We believe he had left accommodation somewhere as he had a single key for a Yale lock. He may not necessarily have been living in Galway and we believe he had been on foot. This is a man who may not have had a lot of worldly possessions,” he said.