Thomas J. Mackell; Queens D.A. Resigned Under Cloud

Thomas J. Mackell, 77, a Queens district attorney who resigned after being indicted in 1973 on charges of hindering prosecution of a scam involving members of his staff. Mackell was a New York police officer and a 12-year member of the state Senate before being elected district attorney in 1966. In 1974, he was found guilty of blocking the prosecution of those operating a $4.4-million pyramid scheme. The conviction later was overturned. In New York City on Sunday of stomach cancer.