The 29-year-old man arrested by Gardai was known to the deceased and was being quizzed by detectives at Midleton Garda Station last night under Section 4 of the Criminal Justice Act
The alarm was raised shortly after 4.15pm on Friday when gardai were informed that there had been an incident at the property.
Ms Walsh was found in the apartment with serious injuries. It is understood that she had injuries consistent with being stabbed.