A man in his 20s has been arrested in London in connection with the hit-and-run death of a father-of-four in Co Kerry in July 2012.
Paud O'Leary was knocked from his bicycle and killed near his home at Gneeveguilla.
He was training for the Ring of Kerry charity cycle, which was due to take place the following week.
Despite extensive investigations, the vehicle involved in the collision, believed to be a grey Toyota Land Cruiser, was never traced.
Nobody has been charged in connection with Mr O'Leary's death.
However, gardaí have been working on the basis that the main suspect in the case fled to Australia.
That suspect is believed to have travelled to London in recent days and he was arrested as he attempted to board a flight back to Australia on Tuesday.
He is being detained in London pending his extradition to Ireland, where he is expected to be charged in connection with Mr O'Leary's death.