The 41 year old man was detained in the city centre just after midday and brought to Tralee Garda Station for questioning.
It's understood the man is related to a 37 year old man who was arrested at Cork University Hospital in the early hours of this morning.
The first man arrested is originally from Cork but is living in Killarney.
The attack on Thomas Dooley happened at a cemetery in Tralee yesterday while a funeral was taking place.
His wife was also attacked and she remains in a stable condition in hospital, after undergoing surgery.