A crowd of about 700 persons, including business and community leaders and some District government appointees, rallied on the steps of the District Building yesterday to protest what they said was unfair treatment of Mayor Marion Barry in the current federal probe of city government contracting.

"If he's guilty, indict him. If not, leave him alone," said rally organizer Calvin W. Rolark, one of several speakers to denounce federal prosecutors for their handling of the probe and news media reports based on unidentified sources. Some suggested Barry was a victim of efforts to undermine black political leadership.

Placards proclaimed "We thought lynching was outlawed," "Where's the beef," "Stop the Leaks" and "Ward 8 Supports Mayor Barry."

"We don't need vigilante law in our city," said lawyer Jack H. Olender, reading a statement from the Trial Lawyers Association of Metropolitan Washington, D.C. "We see trial by jury being subverted by trial by press."

Olender said justice was supposed to be "blind to race, creed and economic and social status. But the blindfold comes off when authorities fail to follow the straight and narrow path toward justice for all."

Barry did not attend the hourlong noontime rally and his aides said he played no part in organizing or promoting it. Barry left yesterday for a five-day vacation in the Bahamas with his son Christopher.

There have been numerous news reports about the federal probe since May 22 when U.S. Attorney Joseph E. diGenova announced the end of a 17-month undercover operation involving an FBI agent who posed as a city contractor.

There have been no arrests or indictments in the probe, which has broadened to include six city agen-"If he's guilty, indict him. If not, leave him alone."

-- Calvin W. Rolark

cies and the federal Department of Housing and Urban Development.

The probe also includes a new examination of the actions of Karen K. Johnson, a convicted cocaine dealer whose relationship to Barry was investigated in 1984.

Johnson, according to sources, has told prosecutors that she took as much as $25,000 in payments to remain silent in the 1984 investigation of alleged illegal drug use by Barry and others. No charges were filed against Barry in that investigation.

"If there is something cooking, there ought to be a straight indictment," said John W. Hechinger, the D.C. Democratic national committeeman and owner of a chain of home improvement stores.

"Enough is enough . . . . It really is trial by innuendo," Hechinger said from the middle of Pennsylvania Avenue, which had been partly blocked off for the event.

Supporters of the rally, some of whom gave brief speeches, were Del. Walter E. Fauntroy (D-D.C.); the Rev. Ernest R. Gibson; former D.C. Council member Douglas Moore; Joslyn N. Williams, president of the AFL-CIO Metropolitan Washington Council; the Rev. Edward Hailes, president of the D.C. branch of the NAACP, and the Rev. Willie Wilson, pastor of the Union Temple Baptist Church.

D.C. Council members Wilhelmina J. Rolark (D-Ward 8), Calvin Rolark's wife, and Harry Thomas (D-Ward 5) also spoke at the rally.

"Let me hear you shout. Are you a friend of Marion Barry?" Rolark asked. The crowd roared back, "Yes!"

Many of those involved also had complained in 1984 that diGenova had unfairly allowed too much of the Johnson investigation to leak to the news media. DiGenova's office generally has declined to comment on complaints about how he is conducting the investigations.

Also yesterday, the D.C. Black Police Caucus complained at a separate news conference at St. Augustine's Church, 14th and V streets NW, that newspaper leaks of hearsay evidence were unfair.

"The grand jury system is a confidential process," said Lt. Lowell K. Duckett, president of the caucus. "A violation of this process . . . is a criminal matter itself."

Last night, friends and associates of David E. Rivers -- a senior aide to Barry who voluntarily went on leave after he was linked to the current contracting probe -- held a $25-a-person reception on Rivers' behalf at Chapter III at New Jersey Avenue and I Street SE. Printed invitations were distributed to various D.C. government employes.