A watchdog investigation into how police handled the controversial on-the-runs scheme for republican fugitives "lacked fairness, lacked balance and lacked thoroughness", a House of Commons committee has been told.
Peter Sheridan, a retired RUC and PSNI Assistant Chief Constable, claimed the report by the Police Ombudsman had been rushed through with "hindsight bias".
"As someone who has read hundreds of investigations the report is in my view written in a way that suggests that conclusions were arrived at first and then evidence to support the conclusions gathered and evidence to the contrary view received little weighting," he said.
Mr Sheridan was giving evidence to the NI Affairs Select Committee, which is holding an inquiry into government letters sent to more than 200 republican paramilitary suspects. He told MPs he would think twice before engaging with the ombudsman or encouraging other former officers to co-operate with his office again.
Ombudsman Dr Michael Maguire examined the PSNI's role in the contentious OTR scheme -established by the Government at the request of Sinn Fein - and in particular officers' handling of the case of John Downey. Mr Downey walked free from the Old Bailey earlier this year when his prosecution for the murders of four soldiers in the IRA's 1982 bomb in Hyde Park collapsed when it emerged he had been mistakenly assured in an official letter that he was able to return to the UK.
The PSNI was heavily criticised for failing to inform the authorities issuing the letter that Downey was wanted for questioning over the Hyde Park outrage.
In his evidence to the committee, Dr Maguire defended the integrity of his report which had been requested by the PSNI Chief Constable.