INVESTIGATORS are to begin interviews within days into allegations by Ian Bailey of serious garda misconduct.
Mr Bailey (54) is suing the State for wrongful arrest, which, if settled, could yield up to €2m in damages.
He lodged a formal complaint with the Garda Siochana Ombudsman Commission (GSOC) last December.
It followed revelations during his Supreme Court appeal against extradition to France in connection with the Sophie Toscan du Plantier (39) killing.
He has always protested his innocence and claims attempts were made to frame him.
The Irish Independent has learnt that the GSOC will examine:
• Recorded claims by a drug user that gardai offered him cash and cannabis if he could provide incriminating evidence.
• How statements were taken from key witnesses, including shopkeeper Marie Farrell, whose information undermined Mr Bailey's alibi. She claims she was under duress.
• Contacts between gardai and state solicitor Malachy Boohig, in which an officer is alleged to have asked him to intervene with the then justice minister to ensure the Director of Public Prosecutions (DPP) sanctioned a charge against Mr Bailey in 1998.
The investigation is likely to be one of the biggest in GSOC history.
It has been backed by Justice Minister Alan Shatter, who said: "I believe that it is clearly desirable that these matters be investigated in the public interest."
The minister is now "consulting" with Attorney General Maire Whelan over last November's disclosure of key prosecutorial documents to Mr Bailey.
They included a 44-page critique in which a DPP official describes the investigation as "flawed and prejudiced".
Addressing that report yesterday, Mr Bailey's solicitor Frank Buttimer said: "I hadn't expected it, I had no entitlement to it.
"It was the actual internal file of the DPP ... I couldn't believe what I was reading."
The GSOC probe could last more than a year, according to a source, due to the sheer scale of the investigation.
"You are talking about almost 16 years of material, not to mention key witnesses who aren't even in the jurisdiction any more," he explained.
With government back-bench pressure for a full public inquiry, the GSOC will move quickly and is likely to interview Mr Bailey within the next fortnight.
The probe takes place as lawyers for French investigators go to Dublin District Court tomorrow in a bid to secure access to copies of Mr Bailey's personal diaries.
Mr Buttimer described the move as "quite curious" in light of the Supreme Court findings.
He added that his client would likely face prosecution in France, even without his attendance in court.
"In France you can be tried for the gravest of crimes in your absence," he said.