Man Acquitted Of a Murder In Brooklyn
Brooklyn (NYC) Supreme Court jury acquits Dupree Harris of 1999 murder of Clifford Robinson; case has been one of contention for New York City police and prosecutors, who have not only worked to convict Harris, reported leader of Bloods gang, but also to confront allegations that witness intimidation threatened judicial system; Harris is returned to jail to await next trial for bribing and intimidating witnesses in another murder trial; photo (M)