Complex sentence: Betty Van Patter (c.1932--December 13,1974) was a bookkeeper for the Black Panther Party and an aide to Panther leader Elaine Brown in 1974, after being introduced to the Party by David Horowitz.
Split into simpler sentences: Betty Van Patter (c.1932--December 13,1974) was a bookkeeper for the Black Panther Party. She became an aide to Panther leader Elaine Brown in 1974, after being introduced to the Party by David Horowitz.