In New Trial, Defense Calls Louima a Liar
Trial of former New York City Police Officer Charles Schwarz on civil rights and perjury charges begins; Abner Louima testifies about incident in Brooklyn police station, when officers sodomized him with broken broomstick; Schwarz's attorney Ron Fischetti focuses on discrepancies in various versions Louima has given at different stages of case and calls Louima liar; prosecutors say defense's attack on Louima is attempt to distract jury from clear evidence that Schwarz participated in attack; chronology of case noted; photo (M)