It's hoped prisoners can help solve a long running missing person’s case.
Posters are to be displayed at Irish jails from this week in relation to the disappearance of Trevor Deely. His brother Mark Deely is an optician based in Castlebar.
Trevor was last seen in Dublin City on December 8th, 2000.
It's believed to be the first time an appeal is being made directly to inmates to solve a missing persons case.
Despite numerous appeals, a 100-thousand euro reward, and a search of land in Chapelizod in 2017, his disappearance remains a mystery.