Former PSNI chief Duncan McCausland sues over 'wrongful arrest'
A former PSNI assistant chief constable questioned as part of an investigation into allegations of bribery is suing the organisation.
Duncan McCausland is seeking damages for wrongful arrest and false imprisonment.
Another former PSNI officer, who went on to become chief constable of West Yorkshire Police, is also taking legal action.
They were two of nine men questioned about the awarding of police vehicle contracts.
None of them faced any criminal charges.
'Aggravated and exemplary damages'
Mr McCausland was one of the PSNI's most high-profile senior officers before his retirement in March 2011.
He has always strenuously denied any wrongdoing and claimed the decision to arrest him as part of the bribery probe in June 2014 was disproportionate, as he had volunteered to assist the investigation.
In a writ lodged in the High Court in Belfast, he accused his former employer of "wrongful arrest, unlawful detention and false imprisonment".
He claimed this was the result of "misfeasance in public office" and is seeking "aggravated and exemplary damages".
A former PSNI constable and two businessmen from England who were also arrested have lodged similar claims.
Another writ has been issued by former West Yorkshire Police Chief Constable Mark Gilmore.
He was not arrested, but was questioned.
A former RUC and PSNI officer, he was appointed chief constable in West Yorkshire in April 2013.
He was suspended on full pay 14 months later after being questioned as part of the PSNI investigation.
That suspension was lifted when he was informed that he would not face any charges.
But, he did not return to his post and retired last year.
Mr Gilmore is suing the PSNI for "aggravated and exemplary damages" for personal injuries and loss caused by misconduct in public office.
It is understood that a number of others arrested during the investigation are also considering legal action.
In a statement, a solicitor for Mark Gilmore confirmed that he has initiated legal action.
"A judicial process has now been embarked upon and it would be inappropriate to offer further comment at this stage," the solicitor said.
When informed in December 2015 that he would not face any charges, Mr McCausland called on the PSNI chief constable to apologise for the way he had been treated.
"This matter can be resolved very quickly in an easy way if Chief Constable George Hamilton, who I know personally, is prepared to offer his regrets for what happened," he told the BBC.
In response, the chief constable said he was "wholly content" with the way police dealt with the case.
In a statement to the BBC, a PSNI spokeswoman said: "In relation to a number of claims arising from a police investigation, PSNI can confirm that it will enter a defence in all cases."