On Sept. 24, a front-page story headlined "The Worst Congressman" appeared in the Village Voice, a New York City weekly newspaper. The congressman was Rep. John M. Murphy (D-N.Y.), who now has been named as a subject in the FBI's undercover "sting" operation.

Nearly two months after the article appeared, Murphy retaliated by asking the Justice Department to investigate the sources of the Village Voice writer, Jace Newfield, and of other critical reporting.

Last night in Manhattan, Newfield said, "I'm pleased that the Justice Department investigated Congressman Murphy more vigorously than it investigated me."

At the time, the department said "there's no investigation of any reporters or any newspapers. . . "

The Newfield article summarized what he described as Murphy's "incredible pattern of trying to enrich himself at the expense of the public interest."

Murphy remains under investigation by various federal agencies in connection with "four or five" of the nearly 10 situations reported in the Village Voice, Newfield said.

One of the charges in the article was that Murphy had represented the interests o Thomas Gambino, a son of last Mafia leader Carlos Gambino.

Murphy, in a $4,500, two-page advertisement in the Village Voice, asserted that the charge was inaccurate.

A second charge was derived from an October 1977 New York Times report that during the 1973-1974 Arab oil boycott, Murphy tried to arrange Iranian financing and supplies of Iranian crude oil for a refinery than being planned in Nicaragua by its president, Gen. Anastasio Somaza.

Initially, Murphy denied that he had any part in promoting the refinery which was to have a Nicaraguan partner-company 98 percent owned by Somoza and which was to have been built at an Atlantic Coast site called Monkey Point. After being reminded by the Times that it had a letter revealing his involvement, Murphy acknowledged it. The refinery was never built.

The congressman and Somoza became friends more than 30 years ago when both were students at LaSalle Military Academy in Oakdale, N.Y., Murphy said. Last summer, before Somoza fled Managua to end a bloody revolt incited in good part by corruption in his government, Murphy went to the capital city to advise Somaza. The American ambassador, entering a room to urge Somoza to resign, found Murphy at his side giving him counsel.

In the Village Voice, Newfield reported that Murphy was under investigation by the FBI for allegedly taking a kickback on a construction contract for the Pahlavi Foundation building in Manhattan. The foundation, an enterprise of the family of the former shah of Iran, numbered Murphy among its directors until the shah was ousted from power.