Where is Ellison Square in Castlebar?

I was in Castlebar on a day trip last week and afterwards I was reading a book by Stephen Rea about crimes in Ireland. Mary Duffy was murdered in a famous case many years ago and the book says she used to work in Elisson Square in Castlebar. I was curious about this as thanks to Google Maps I discovered that I parked in Elisson Street by coincidence on my trip. Is there a place in Castlebar called Elisson Square or does does the writer actually mean Elisson Street?

(Who was Elisson anyway?)

Thanks.