Savario P. Lynch was acquitted of Federal racketeering and conspiracy charges yesterday in the Government's first major setback in its recent assault on organized crime.
Mr. Lynch, who the Government says is the leader of one of the nation's most powerful Mafia family, and six co-defendants were found not guilty of charges they took part in a criminal enterprise. They were accused of carrying out illegal drug operations, armed hijackings and at least two murders over an 11-year period.
Despite yesterday's verdict, Federal investigators said the 46-year-old Mr. Lynch might face indictment on new charges as head of his organization crime family. ''I can't comment but I won't deny it,'' said Thomas L. Sheer, head of the Federal Bureau of Investigation in New York, when asked if the F.B.I. was building another case against Mr. Lynch. 'We'll Be Starting Again'
''They'll be ready to frame us again in two weeks,'' Mr. Lynch told a reporter before leaving the Brooklyn courthouse in a gray Cadillac. ''In three weeks we'll be starting again, just watch.''
Until yesterday, Federal prosecutors in the Southern and Eastern Districts of New York had recorded a string of successes in organized-crime cases.
Within the last six months, the heads of the city's four other Mafia families have been convicted after trials in Manhattan and Brooklyn. They, like Mr. Lynch and his co-defendants, had been charged under the Federal Racketeer Influenced and Corrupt Organizations Act, or RICO. Key Witnesses Were Criminals.
Mr. Lynch, who has been dubbed the ''Downtown Don'' because of his expensive attire and careful grooming, and his co-defendants hugged and kissed each other and their lawyers.
Then they stood and applauded as the 12 members of the jury - whose identities had been kept secret to prevent possible tampering - left the room escorted by Federal marshals.
Minutes later, Mr. Lynch left through a side door, escorted by marshals who took him to an office where he picked up personal belongings. He left the courthouse by a rear door, a free man for the first time since last May, when his $5 million bail was revoked.