Police in Northern Ireland are to seek the entirety of the controversial US oral history project that detectives relied upon to quiz Sinn Fein’s Gerry Adams about a notorious IRA murder.

The Police Service of Northern Ireland (PSNI) last year won a legal battle to secure taped interviews with former paramilitaries contained in the Boston College Belfast Project that specifically referred to the killing of mother of 10 Jean McConville in 1972.

But the material handed over only accounted for a small portion of the entire archive.

Dozens of former paramilitaries, both loyalist and republican, gave accounts of their involvement in the Troubles on the understanding their interviews would not be made public until after their deaths.

But that assurance was undermined when a US judge ordered that audio tapes that referenced Mrs McConville be handed over to detectives from the PSNI.

The police said it was now going to pursue the rest of the collection.

A PSNI spokeswoman said: “Detectives in Serious Crime Branch have initiated steps to obtain all the material from Boston College as part of the Belfast project. This is in line with PSNI’s statutory duty to investigate fully all matters of serious crime, including murder.”

US news network NBC is also trying to secure access to the archive on the grounds of public interest.

Mr Adams, who vehemently denies any involvement in Mrs McConville’s murder, was quizzed by detectives for four days earlier this month.

Prosecutors in Northern Ireland have been asked to assess a police file to decide if any charges will ultimately be brought against the Sinn Fein president.

Mr Adams has claimed most of the evidence detectives presented to him in Antrim police station about Mrs McConville’s death was based on allegations levelled by project interviewees, two of whom were the now deceased former IRA members Brendan Hughes and Dolours Price.

Amid uncertainty about the status of the tapes still held in the archive, Boston College had offered to return the material to those individuals who have given interviews.

Some of the interviewee have threatened to sue the college over its handling of the issue.

Journalist and published author Ed Moloney worked on the archive with former IRA member turned writer and academic Anthony McIntyre. They were effectively sub-contracted by the college to undertake an initiative it agreed to fund and store.

Both have subsequently criticised the college, claiming it did not robustly challenge the initial PSNI court bid — allegations the college has rejected.

PA