Who is Victor Mattiece from The Pelican Brief and what is their importance?

Victor Mattiece is the multi-millionaire whom Darby Shaw names as the man behind the Rosenberg/Jensen murders, Mattiece owns a half-dozen homes in as many countries, jets, and boats, and is rarely in the U.S. Had Mattiece not gone berserk and started killing people, the "pelican brief" would have been ignored. With the probable gunman, Khamel, dead, the probable bagman elusive, and the conspirators gone, the FBI and CIA concentrate on finding Mattiece.