Complex sentence: University of Southern California Law School professor W. David Slawson was an associate at Davis Graham when President Kennedy was assassinated the firm granted him what was expected to be a 2-3 month leave of absence to work for what soon became the Warren Commission.
Split into simpler sentences: University of Southern California Law School professor W. David Slawson was an associate at Davis Graham when President Kennedy was assassinated. The firm granted him what was expected to be a 2-3 month leave of absence to work for what soon became the Warren Commission.