Gardaí are investigating the alleged rape over the Christmas period of a young woman in Castlebar, Co Mayo.
An investigation began after the woman, who is in her twenties, presented in a distressed state to Castlebar Garda Station in the early hours of Thursday morning.
She was accompanied by a relative who had come to pick her up after a night out in the town.
Later the woman was brought to the sexual assault unit in Galway City for a medical examination and gardaí carried out a forensic examination of the area - a laneway near Castlebar town Centre - where the alleged sexual assault took place between 2 am and 2.30 am.
Gardaí say their investigations are ongoing and they are following a definite line of enquiry.
CCTV footage has been obtained and is being studied by gardaí as their investigation continues.