The two men arrested over the suspected theft of confidential documents relating to the 1994 Loughinisland massacre have been named as journalists and documentary film makers Barry McCaffrey and Trevor Birney.
The two men, who have spent years investigating Loughinisland, were detained in Belfast on Friday morning, and are being questioned at Musgrave Police Station.
The documents allegedly taken relate to a police investigation into the murder of six men in 1994.
The documents were allegedly used in the research of the film No Stone Unturned, released in November last year, produced by Mr Birney and award-winning documentary maker Alex Gibney.
Former Andersonstown News and Irish News reporter, Barry McCaffrey, 48, has been researching the Loughinisland atrocity for more than 10 years, and has been a fixture in Irish media for over two decades.
Some of Mr McCaffrey’s most prominent work was related to the 2004 Northern Bank heist in Belfast.
Mr McCaffrey previously worked for The Detail, an investigative news website which has carried a number of stories regarding Loughinisland, as well as a number of other investigations.
Mr McCaffrey was awarded the overall justice media award in the Attorney General’s Justice Media Awards in 2013.
The award recognised his investigation into the use of solitary confinement in Northern Ireland’s prisons.
In the same year, Mr McCaffrey was named digital journalist of the year.
The searches linked to Friday’s arrests have been carried out at Upper Arthur Street where The Detail news website and Fine Point Films are based.
The award-winning producer and director Mr Birney, 51, founded Fine Point after 20 years working in the media.
Mr Birney began his career in Enniskillen on the Impartial Reporter newspaper and has also worked in radio.
Since then, he has produced a number of documentaries and series for Irish, UK and international broadcasters.
He was a co-producer on the Oscar-shortlisted, Alex Gibney feature-documentary, Mea Maxima Culpa: Silence In The House Of God, for which he received an IFTA in February, 2013.
He was nominated for an Emmy for his feature documentary, Elian, produced by Belfast-based Fine Point.
In 2006, Mr Birney founded Belfast-based production company Below The Radar where he produced a range of English and Irish language programmes, including political biographies and historical documentaries.
He is the former editor of current affairs at Ulster Television.
He has also won a justice media award, two Royal Television Society awards, been nominated for three others and was named NI Broadcaster of the Year in 2002.
Police say the material had been in the possession of the Police Ombudsman for Northern Ireland.
The two men were arrested by officers from the Durham force.
A number of documents and computer equipment seized during the raids will be examined by specialist officers.
A spokesman for Durham Constabulary described the investigation as “complex”.
Six people were killed on June 18 1994 when loyalist gunmen burst into a bar in Loughinisland, Co Down, and opened fire on customers.