The Garda Ombudsman is set to probe the force’s investigation into Cork moneylender Ted Cunningham, whose conviction for laundering £3m from the Northern Bank raid was quashed last week.
Mr Cunningham walked free on Friday, three years after he became the only person to be convicted in connection with the Dec 2004 Belfast robbery.
Quashing his conviction, the Court of Criminal Appeal ordered a retrial against Mr Cunningham on nine charges of money laundering.
However, he will not be retried on the 10th charge, relating to £2.4m (€2.9m) allegedly found in a cupboard of his home in Farran, Co Cork, on Feb 17, 2005.
The judgment was based on a Supreme Court ruling that a particular type of search warrant — used in the Farran search — was unconstitutional.
Mr Cunningham was jailed for 10 years in Apr 2009.
The 63-year-old lodged a complaint with the Garda Síochána Ombudsman Commission two months ago, containing allegations regarding Garda behaviour during the investigation.
The commission has assessed the complaint and is expected to announce an investigation shortly. The investigation will progress independently of the retrial.
It is the latest highly sensitive probe to be set up by the commission. Last February, GSOC said it was setting up a public interest inquiry into the Garda treatment of Ian Bailey in the Sophie Toscan du Plantier murder probe.
A spokesman for GSOC confirmed yesterday it had received a complaint from Mr Cunningham.
Separately, Mr Cunningham told a Sunday newspaper he intended to sue the State and the prison authorities. He claimed he had to contend with a threatening, bleeding condition in an overcrowded cell, where he had to share slop-out toilet buckets.
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