A prison officer planted a note of personal details about a governor in Northern Ireland in the cell of a dissident republican suspect, the ombudsman said last night.
The information was found in the Maghaberry prison unit in September 2009 and the PSNI has begun an investigation into the matter.
Then-governor Steve Rodford resigned a short time later because of fears he was under threat.
Ombudsman Pauline McCabe has completed an 18-month investigation into the incident.
"On the balance of probabilities, a member of Prison Service staff planted the note found in Mr (Brendan) McConville's cell," her report said. "On the balance of probabilities, the note was planted in Mr McConville's cell to try to encourage the governor of Maghaberry prison to reconsider planned changes he was proposing to make at the prison.
"The fact that the note was found in the cell of a republican prisoner was not believed to be a coincidence, but no evidence was found that there was an intention to target Mr McConville's cell in particular."
Brendan McConville is charged with the murder of PC Stephen Carroll in Craigavon two years ago.
Shortly before Mr Rodford left, the piece of toilet tissue was discovered in the cell of McConville. It contained the governor's name and car registration.
Ms McCabe added: "There are reasonable grounds to indicate that one member of prison staff may have committed a disciplinary and criminal offence and the attention of the Minister of Justice (David Ford) and PSNI should, in line with the obligations placed upon the Prisoner Ombudsman, be drawn to this."
A lawyer for McConville wrote to the Ombudsman alleging that his client had been set up by staff opposed to change, leading to the investigation.
The police investigation will be undertaken by a district detective, rather than one from the unit involved in the original inquiry.
A PSNI spokesman said: "We have received a copy of the report and have begun an investigation."
PA