A librarian with Kildare Library Services, Mario has written and edited many books on the history of Co. Kildare and his hometown of Kildare. He has written four children’s books with children in schools in Kildare, Listowel and Roscommon, all of which were illustrated by David Butler.
As part of his work on the Decade of Centenaries project in Kildare he has written a play A Terrible Beauty Exposed! and a narration for a series of concerts, Birth of a Nation, which included a performance in Lexington, Kentucky, USA.
On 9 July 2022 he delivered the oration at the centenary commemoration for Cathal Brugha in Glasnevin Cemetery.