Another Kinahan hitman-for-hire is suspected of carrying out the violent attack on Smyth last Sunday.
Investigations have started into the incident in Castlerea Prison, during which Caolan Smyth (30) was also beaten with a sock filled with batteries.
The violent criminal is currently serving a 20-year sentence for the attempted murder of Hutch gang associate James 'Mago' Gately in 2017.
sundayworld.com has learned that another Kinahan hitman-for-hire is suspected of carrying out the violent attack on Smyth last Sunday.
Authorities believe Glen Thompson (28), from Finglas, north Dublin, was the inmate who targeted Smyth and scalded him on the landing they shared.
Thompson is serving a lengthy sentence for his role in a plot to murder the brother of Gerry 'The Monk' Hutch over four years ago.
He is believed to have used a kettle to throw boiling water over Smyth.
A source said: "The background to this incident is still being looked at, whether it was an argument that escalated or if there is something more to it.
"They are both serving sentences for crimes linked to the Kinahans and also have ties to the Finglas area.
"It may be that this is connected to ongoing threats to Smyth, or a personal dispute between the two that led to him being beaten and scalded.
"The very nature of the incident shows that there was some degree of planning involved.”
Both men also previously had links to the gang led by Finglas drug dealer 'Mr Flashy'.
Glen Thompson had only been transferred to the Roscommon jail in recent months after being disciplined over a booze-up in Mountjoy Prison.
He and another inmate were caught drinking whiskeys and beer before officers discovered their contraband.
It's understood that since Sunday's assault, Thompson has been transferred back to the north Dublin jail.
A spokesman for the Irish Prison Service said they do not comment on individual prisoner cases.
Thompson and his brother Gary (37) are both serving 12-and-a-half year prison sentences for their roles in a plot to murder Patrick 'Patsy' Hutch, the older brother of Gerry 'The Monk' Hutch, in 2018.
The Thompsons and Afghan war veteran Robert Browne were part of a Kinahan "hit for hire" gang that was arrested near their target’s home that March.
They were members of a 10-man 'sub-cell' hired by the Kinahan gang to murder Patsy Hutch but their every move was being watched by gardaí over several weeks before the plot was foiled.
Fellow gunman-for-hire Caolan Smyth is serving a 20-year jail term after the Special Criminal Court found he was the man who fired five shots into James Gately outside a north Dublin filling station in 2017.
Gardaí believe that shooting was carried out on the orders of the Kinahan crime gang who blame 'Mago' Gately for involvement in the Regency Hotel murder. He has never been charged in relation to this offence.
After he was sentenced, Smyth told his family members in court: "Five world cups and I'll be out."
Smyth survived at least one credible threat to his life when gardaí foiled a plot in September 2019 to murder him. This planned shooting was in revenge for the murder of Sean Little the previous May.