The note was alleged to have been planted in a cell at Maghaberry Prison The lawyer for a man in whose cell a prison officer is alleged to have planted a note has said the police and justice minister must conduct a thorough investigation.
The note is believed to have contained personal details about the former Governor of Maghaberry prison.
It was found in the cell of dissident republican suspect Brendan McConville.
His solicitor, Kevin Winters, said his client believed he “was set up”.
He also said Mr McConville would challenge the case against him over the murder of PSNI officer Stephen Carroll.
The note was found in the suspect’s cell in December 2009.
The governor at the time, Steve Rodford, resigned a short time later because of fears he was under threat.
Prisoner Ombudsman Pauline McCabe has completed a 15-month investigation into the incident.
She concluded the note was hidden in the cell by a member of staff opposed to planned reforms at the prison.
Mr Rodford resigned less than five months after he was appointed.
Security was one of the factors in his decision as his wife had left Northern Ireland weeks earlier because of concerns they were being targeted by dissident republicans.
The ombudsman has now said that, “on the balance of probabilities” the note was planted in the cell by a member of prison service staff and that the purpose was to encourage the governor to reconsider the planned changes.
Ms McCabe has also concluded that prison staff leaked incorrect information to the media that Mr Rodford was being actively targeted by dissident republicans.
The ombudsman said there were reasonable grounds to indicate that one member of staff may have committed a disciplinary and criminal offence.
The police have now launched a criminal investigation.
In a statement, the prison service said it took the matter very seriously and had launched a disciplinary investigation, which has been adjourned until the police complete their inquiry.
It confirmed it had received a copy of the Prisoner Ombudsman’s report following a complaint by prisoner Brendan McConville.
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