Before the march , Steven A. Pagones , a former assistant prosecutor in Dutchess County who won a defamation suit against Mr. Sharpton and two others in 1998 , showed up near the marchers ' rendezvous point to remind reporters that he had been falsely accused of being one of a group of white men who abducted and raped a black teenager , Tawana Brawley , in Wappingers Falls , N.Y. , in 1987 .