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 record.
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 are now going to pursue the rest of the collection. A PSNI spokeswoman said: "Detectives have initiated steps to obtain all the material from Boston College. This is in line with PSNI's statutory duty to investigate fully all matters of serious crime, including murder."