Today the ombudsman published a 344 page report into the RUC's handling of attacks committed by loyalist paramilitary group the Ulster Defence Association (UDA) in Belfast during the 1990s.
The crimes involve the deaths of 11 victims, including five who died in the attack on the Sean Graham bookmakers on the Ormeau Road in February 1992.
Anderson said the investigation found that Royal Ulster Constabulary (RUC) files relating to the Sean Graham attack had been destroyed on purpose.
The RUC Special Branch was found to have used informants who were involved in the attacks. Eight RUC informants had been linked to 27 murders and attempted murders.
"This was totally unacceptable, and an illustration of how on occasion, the interests of obtaining information from informants was given precedence over the protection of the public from paramilitary crime and murder," she said.
Anderson questioned why no information had been received by the RUC that would have prevented the attacks, given they were using informants involved in the crimes.
She said the report found evidence of "collusive behaviours" including failing to warn potential victims of threats on their lives; intelligence failings that allowed loyalist paramilitaries to obtain military grade weapons; a failure to act on evidence; failure by the Special Branch in relaying intelligence to homicide investigators; and turning "a blind eye" to the activities of informants.
"I am of the view that the absence of controls, combined with the absence of records relating to these informants, constitutes collusive behaviour," Anderson said.
