A Washington lawyer, described as the "consigliere" of an alleged multimillion dollar heroin ring, pleaded guilty in federal court here today to conspiracy in the mammoth drug trafficking case.

The unusually swift action against Herbert Philip Suskind, 49, who was indicted only two weeks ago, came after sensitive negotiations between prosecutors and Suskind's lawyer, in which the government agreed to drop other charges in the indictment against Suskind and not require him to testify against the 13 other persons indicted in the case.

At the same time, however, Suskind agreed to plead guilty to two additional charges. One is a charge of defrauding the U.S. government in connection with preparing false tax returns for two undercover narcotics agents involved in the alleged heroin ring. The two agents, according to prosecutor Ty Cobb, posed as heroin dealers and arranged with Suskind to "launder" thousands of dollars in presumed drug revenues through video game investments in the Washington area.

The second additional charge was mail fraud, in connection with an alleged phony auto accident-medical insurance scheme under investigation by a federal grand jury here. Indictments or guilty pleas against other participants in the alleged scheme are expected soon.

Suskind, a longtime Washington attorney, faces up to 25 years in prison and $36,000 in fines on the various charges.

Jailed on a $2 million bond since his arrest on April 22, Suskind was reported by his lawyer, Carl Fogel, to have been released late today after federal Judge Alexander Harvey II agreed to let him put up his Bethesda home, valued at approximately $200,000, as collateral.

Suskind was indicted April 22 along with his brother, Richmond accountant David Norman Suskind, Isaac J. Tindle, an alleged heroin kingpin in Prince George's County, and 11 other suspects in what prosecutors described as a huge Mafia-supplied drug operation in the Washington area.

At the time of his arrest, Cobb called Suskind the "consigliere" counselor of the operation, who with others laundered illicit revenues through a network of video game parlors in the Washington area.