A 49-year-old man was arrested and questioned in Co Mayo about the alleged rape of a woman in her 70s in Ennis, which occurred last week.
Gardaí in Co Clare were informed of the alleged sexual assault last Thursday afternoon.
The suspect was identified as a result of a trawl of car movements on CCTV footage throughout the Ennis area.
He was arrested in Co Mayo the following day and questioned about the incident.
He was released on Saturday and a file on the investigation is being prepared for the Director of Public Prosecutions, which will decide if the suspect will face charges.