In 1979, after a review of the evidence and of prior investigations, the United States House Select Committee on Assassinations (HSCA) largely concurred with the Warren Commission and was preparing to issue a finding that Oswald had acted alone in killing Kennedy. However, late in the Committee's proceedings a dictabelt recording was introduced, purportedly recording sounds heard in Dealey Plaza before, during and after the shots were fired. After an analysis by the firm Bolt, Beranek and Newman appeared to indicate more than three gunshots, the HSCA revised its findings to assert a "high probability that two gunmen fired" at Kennedy and that Kennedy "was probably assassinated as the result of a conspiracy." Although the Committee was "unable to identify the other gunman or the extent of the conspiracy," it made a number of further findings regarding the likelihood or unlikelihood that particular groups, named in the findings, were involved. Four of the twelve members of the HSCA dissented from this conclusion.