A Lynn man charged with armed robbery in connection with the $5 million coin theft at the Fogg Art Museum pleaded innocent yesterday in East Cambridge District Court.

Cambridge police arrested the man, Leonard J. Piazza, Thursday night outside a store in Lynn. A police source said the arrest was made after Cambridge police showed a composite drawing of the man to the Lynn police.

The Lynn police knew of the suspect and "where he hung out," the source said. Judge Harry M. Lack continued the case and set bail at $10,000. Piazza posted the bail and was released.

Another Warrant

The police also hold a warrant for the arrest of an East Boston man in connection with the robbery. The police have composite drawings of four suspects, made from descriptions provided by a Fogg guard and a woman who saw the thieves.

The thieves broke into the Fogg at 12:30 a.m. Sunday, stealing 5600 ancient Greek and Roman coins from the Fogg's thirdfloor coin room.

The silver, gold, and bronze coins were minted between the seventh century B.C. and the fourth century A.D.

The FBI and the police say they have located two of the remaining suspects and have put the men under surveillance.

The police source said that the investigation has not led the police outside Massachusetts. More than 40 FBI agents are assisting in the case.