Sheehan was fatally shot in County Clare in 2012.
Gardaí and Crimestoppers have launched an appeal for information in relation to the death of Robert Sheehan in Bunratty, County Clare six years ago.
The incident will feature on Monday night's Crimecall programme on RTÉ One.
On Sunday 2 September 2012 at approximately 3.40am, Sheehan was fatally shot a number of times in the car park of the Bunratty Castle Hotel.
Crimestoppers and the Gardaí are asking for people who know anything of relevance to this case to contact them.
Calls to Crimestoppers are completely anonymous and callers do not need to leave their name or address.
Anybody with information can call Crimestoppers on 1800 250 025.
"It is now over six years since Robert’s murder," began Detective Sergeant Kevin O’Hagan of Shannon Garda Station in a statement on Monday morning.
"We are appealing for anyone with information to come forward. Do you have knowledge of the events leading up to the shooting or following the shooting?
"You might have information that you may previously have felt you could not come forward with but now with the passage of time, you may believe that now the time is right to share that information.
"Even the smallest piece of information, which may seem insignificant, could help close this case and bring justice to the family.
If a member of the public prefers to give the information without identifying themselves, they can call Crimestoppers on 1800 25 00 25.”
Crimestoppers Chairman John Murphy commented:
"Crimestoppers is here for the public to provide information anonymously that could help solve a crime. You do not need to provide any details about yourself."
If you have information in relation to Robert Sheehan’s death, I would urge you to contact the confidential Crimestoppers number."
