The Parallax View (1974)

Joe Frady is a determined reporter who often needs to defend his work to colleagues. After the assassination of a prominent U.S. senator, Frady begins to notice that reporters present during the assassination are dying mysteriously. After getting more involved in the case, Frady begins to realize that the assassination was part of a conspiracy somehow involving the Parallax Corporation, an enigmatic training institute. He then decides to enroll for the Parallax training himself to discover the truth.