A Dorchester woman has been charged with murder in the August stabbing death of 73-year-old Winston Fields of Roxbury. The suspect — Angeliea Brown, 33, of Dorchester — is currently incarcerated at the South Bay House of Correction on unrelated charges. Fields was found dead Aug. 14 at a residence on Washington Street in Roxbury. An autopsy determined he had been stabbed to death. Brown is scheduled to be arraigned Friday in Roxbury District Court. On Aug. 11, Brown was arrested in Roxbury for “transferring the contents of one bag of heroin into several smaller bags on the steps of Madison Park High School,” said Jake Wark, spokesman for the Suffolk district attorney’s office.