Billy Wright was murdered in the Maze Prison in December 1997
Thousands of documents relating to the murder of LVF leader Billy Wright went missing or were deliberately destroyed, an inquiry has been told.
The claim was made by a lawyer acting for the Wright family.
It is the first day of full public hearings in the inquiry, which is expected to last for a year.
Chairman Lord MacLean said they had hoped to reach this stage much sooner, but progress had been delayed because of a number of factors.
He said one of these was the speed at which material had been provided to the inquiry.
This issue was also taken up by the inquiry's lead counsel, Derek Bachelor QC.
Mr Bachelor said they had experienced delays and difficulties in the recovery of documents and records, particularly from the PSNI.
He said the police had been issued with four formal notices to hand over documents to the inquiry which dated back to November 2005, but were still providing large amounts of evidence as recently as two weeks ago.
The lawyer also said there were gaps in the documents supplied by the prison authorities and the security services.
The inquiry was set up following an investigation by retired Canadian judge Peter Cory into collusion allegations.
The LVF leader was shot dead by INLA prisoners who ambushed him inside the high-security Maze prison in 1997.
Wright had got into a prison van to be taken to the visitors' area of the jail, when the INLA prisoners climbed over the roof of the H-block and into the prison yard.
One opened the van door, singled out the LVF leader and shot him several times.
David Wright claims there was collusion in his son's death
Three INLA prisoners were later convicted of the killing.
Wright's father, David, claims the killing was the result of collusion.
A preliminary hearing was held two years ago, and the main oral hearings began on Wednesday at Banbridge court house.
The inquiry is expected to last for up to a year.