Lawyers for the man who killed Dublin teenager Melanie McCarthy McNamara in a drive-by shooting have said he is going to end up at the Central Mental Hospital, if his prison conditions are not improved.
The Court of Appeal has heard Daniel McDonnell from Brookfield Lawns, Tallaght is in solitary confinement at Wheatfield prison and is likely to remain there indefinitely.
Daniel McDonnell is serving life for the drive-by murder of 16-year-old Melanie McCarthy McNamara in 2012.
He has been described as probably the most at-risk prisoner in Ireland.
In February a High Court judge ruled his year-long solitary confinement, under 23-hour lock-up at Wheatfield Prison, breached his constitutional rights to bodily and psychological integrity.
A subsequent ruling concluded he needed more time out of his cell and more social interaction, as there was incontrovertible evidence his mental health was suffering.
Both decisions are now being appealed by the prison authorities, who have said he is at risk and cannot mix with other inmates because he has fallen out with two former associates on the wing.