The man was arrested yesterday as part of an ongoing operation which saw six men rescued in Letterkenny last month.
Those men were employed in a number of businesses around the town.
It is alleged they did not have control over their passports and were not paid for the work they were doing.
Stephen Maguire, editor of the Donegal Daily, says they were living in cramped conditions.
“So many of them living in the one flat and stuff – it was off an area of Pearse Road, which is a local area in the middle of Letterkenny” he said.
“We understand conditions were very cramped and that (they had) very little English”.
“It's all these circumstances thrown together then that aroused Gardaí suspicions” he added.
