Files detailing the exact cost the Stevens investigation into allegations that security forces plotted with loyalist paramilitary killers have been lost, it emerged today.
Police could only track down financial records for the latest of Metropolitan Police Commissioner Sir John Stevens's three inquiries since he began examining Belfast solicitor Pat Finucane's murder.
Outraged unionists accused the authorities of trying to cover up a huge cost of the investigations.
Nearly £4.5 million has been spent on Mr Stevens's third investigation which found widespread collusion between Special Branch, military intelligence and the Ulster Defence Association gunmen who killed Mr Finucane in February 1989.
But efforts to uncover the full costs of the 14-year inquiry have drawn a blank.
The Policing Board was told by the Police Service of Northern Ireland its papers only date back to 1999.
In a letter to members, a senior official on the monitoring authority said: "Despite extensive searches the account files for earlier inquiries cannot be located.
"It has only been possible for police to provide the costs for Stevens III.
"In April 1999 the finance function of the former Police Authority transferred to the then Royal Ulster Constabulary.
"It is assumed the files also moved but as a consequence of the reorganisation they cannot be located."
Mr Sammy Wilson, a Democratic Unionist board member opposed to the Stevens investigation, claimed the authorities were too embarrassed to reveal a total bill he believed was close to £15 million.
"People are trying to run away from revealing the full costs of this politically motivated inquiry," he said.
Mr Alban Maginness, a senior member of the SDLP, insisted all costs were worthwhile.
He said: "Anybody that thinks the Stevens inquiry is not a serious, properly constituted police investigation is quite wrong and being quite perverse.
"Much of what was alleged has been validated by Stevens and the costs are justified in terms of getting at the truth."
PA