Police in Northern Ireland seized documents relating to the alleged pedophile priest Fr Finnegan while investigating the unrelated documentary "No Stone Unturned."

Northern Ireland film creator Trevor Birney has accused police of overstepping the mark after they seized confidential documents he believes should be protected by journalistic privilege. 

Birney and fellow journalist Barry McCaffrey were arrested in August 2018 as police investigated an alleged theft of a police watchdog document that appeared in their film "No Stone Unturned."

The groundbreaking movie revealed for the first time the names of the suspects involved in the Ulster Volunteer Force killing of six Catholic men in a village pub in Loughinisland. The filmmakers were accused of theft, however,  after information contained in a Police Ombudsman for Northern Ireland document appeared in the film. Birney and McCaffrey have insisted the information was leaked to them

Police raided the offices of producers at Fine Point Films in Belfast with a warrant allowing them to remove any material relating to the documentary but Birney has now revealed that further documents containing confidential evidence relating to alleged pedophile priest Fr Finnegan were also seized during the raid. 

Read more: Documentary sheds light on the 1994 World Cup Loughinisland Massacre

The evidence in question had been gathered by sister organization The Detail which shares an office with Fine Point Films and contained stories from those who had allegedly experience abuse at the hands of the cleric, who died in 2002. 

“We are working with victims of clerical sex abuse in Northern Ireland and we have very sensitive documents belonging to some of those people who have suffered as a result of abuse and yet those documents were seen as of interest to the police,” Birney told the Irish Times.

“They knew they had nothing to do with 'No Stone Unturned,' they knew they had nothing to do with the Loughinisland investigation, but they decided to take them, despite the fact that their warrant was only in relation to 'No Stone Unturned' they still decided to take those documents.”

Also seized were materials related to investigations on street gangs in Honduras, Farc rebels in Columbia and the conflict in Gaza.

“There are lots of very, very sensitive interviews, each and every one of those films, each and every one of those contributors has to be aware now that our security has been breached and we have been compromised by the actions of the PSNI and I really don’t think the PSNI took any of that into account,” Birney said.

Read moreNorthern police dirty tricks exposed in arrests of two investigative journalists

Durham Constabulary, which oversaw the operation, however, has insisted it had the legal authority to remove material unrelated to Loughinisland.

“Under the Police and Criminal Evidence Act 1984 (PACE), when a constable is lawfully on premises, officers can seize any material while on those premises if they have reasonable grounds to believe that the material has been obtained as a consequence of a commission of an offense, or is evidence in relation to an offense and that it is necessary to seize it in order to prevent it being concealed, lost, altered or destroyed,” said a spokeswoman for Durham Constabulary.

“While present on premises by way of a warrant execution, the seized material does not need to relate to the offence for which the search warrant was granted.

“The warrants carried out at these particular addresses were signed by a judge and the items were seized after a dialogue with, and with full knowledge of, the managing director of the business premises concerned.

“Under normal circumstances, materials such as this that are seized during a search are assessed and evaluated.

“However, we have been unable to do this as a result of the undertaking given during the judicial review process brought about by Fine Point Films.”

Evidence collected is currently in storage pending the outcome of a High Court challenge into the police's use of the warrant. 

Trevor Birney and Alex Gibney attend the 55th New York Film Festival - 'No Stone Unturned' at The Film Society of Lincoln Center, Walter Reade Theatre on September 30, 2017, in New York City.PAUL ZIMMERMAN/GETTY