Published Tuesday, 10 August 2010
On Monday night, officers searched Mr Gilligan's south Belfast home and board office.
A number of unspecified items were taken by detectives investigating a land deal involving Mr Gilligan's property company - Big Picture Developments.
The father of three was expected back at the Policing Board Headquarter next week following six months of recuperation after heart surgery.
But Mr Gilligan has now postponed his return to office until the criminal investigation is over.
In a statement released to UTV, Mr Gilligan said he would continue to co-operate fully with police.
"My fellow directors and I have made, and continue to make, ourselves and our company files totally available to the PSNI in order to clear matters up as speedily as possible, confident that we will be completely vindicated.
"It had been my intention to return to my role as Chairman before the end of the summer but in light of the recent activity by the PSNI, my coronary condition and the dignity of the office of Chairman of the Northern Ireland Policing Board, I feel that I should not return to the role at this time."
Mr Gilligan said it was still his intention to return to his position as board chair "as soon as possible" and that he would be seeking support from his fellow members of the police oversight body.
"I will seek that support from the Board at its meeting on 2 September 2010," he said.
Ulster Unionist Policing Board member Basil McCrea has described the situation as "very delicate".
"Everyone is entitled to the presumption of innocence and whilst there is no suggestion of impropriety on the part of Barry Gilligan, it is clear that the fact of a PSNI search on Policing Board premises is a matter of public interest," Mr McCrea said.
"Many significant issues are facing the Northern Ireland Policing Board at present, not least the finances of the PSNI and an ever worsening security situation.
"It is imperative that the good work of the Policing Board is allowed to continue, unhampered by this investigation."
Detectives were called in five months ago by the Northern Ireland Housing Executive to investigate the sale of a site in Nelson Street, Belfast to Big Picture Developments.