City investigators have completed interviews with several key workers in Mayor Walter E. Washington's 1974 election campaign without asking them about some of the alleged secret cash payments that are supposed to be the focal point of their investigation, according to knowledgeable sources.

The sources said some of the persons interviewed by city Campaign Finance Director Carl McIntyre had first-hand knowledge of how at least $1,400 - some of it in =100 bills - was used to pay salaries of campaign workers but not reported as required by law.

Some of these persons were prepared to tell investigators details of the alleged cash payments, the sources said. But the only questions asked were general ones about campaign law violations that may have occured after Aug. 14, 1974, the day a new D.C. campaign finance law became effective.

McIntyre, who has been conducting the investigation for the past five weeks, said he has chosen Aug. 14 as a cutoff date because he believes his office has no authority over compaign matters before then. Much of the financial activity in the 1974 mayoral campaign, which was virtually decided by the outcome of the Sept. 10 Democratic primary, took place before Aug. 14.

Before August the 14th I didn't exist," McIntyre said in a recent interview, "That's just like asking me how can I enforce slavery today.?

Shari B. Kharasch, chairman of the city's Board of Elections and Ethics, said the board questions McIntyre's more narrow interpretation and has asked the board's general counsel for an advisory opinion on jurisdiction before Aug. 14. Yesterday, for the second time in two weeks, the board rejected McIntyre's report on the alleged campaign violations on grounds that it lacked key information.

Sources familiar with the city's campaign law say that it clearly gives the elections board authority to investigate allegations of campaign violation that took place before Aug. 14. This includes, the sources said, violation of a 1971 law requiring that all expenditures of $50 or more be reported.

The Office of Campaign Finance, which is part of the elections board, is the primary agency to which the D.C. Code gives authority to investigate and monitor election activities. The office has the power to subpoena documents and interview witnesses under oath, which it has not done so far.

The Washington Post reported Dec. 23 that, according to knowledgeable campaign sources, at least $1,400 in secret cash payments were made to campaign workers before Aug. 14. The investigation, which is officially called a "preliminary inquiry," was ordered by the board Dec. 27 to determine if there was sufficient merit in the published allegations to warrant a full-fledged investigation.

Sources have told The Post that the alleged cash payments were made at a time when managers of the mayors well-financed campaign were worried about meeting regular campaign expenses without exceeding a $120,000 primary campaign spending limit imposed by Congress.

The sources said city administrator Julian Dugas, the mayor's closet political cofidant, gave the money to campaign coordinator John Dean who then used the money to pay salaries of campaign workers. The payments took place in July and August of 1974, the sources said.

"I don't think the board accepted those dates as the dates they took place. I know I didn't," McIntyre said.

McIntyre would not say which of the persons he interviewed was asked about events before Aug. 14. "In the beginning, I didn't even think about a date," he said. "But I'm not interested in what happened before that (Aug. 14). I'm not investigating that. I have no authority.

Ever since the investigations was first ordered by the elections board in a unanimous vote Dec. 27, the inquiry has fallen behind a schedule set by the board that would have required McIntyre to report his findings within two weeks.

According to sources close to the board, McIntyre has had problems arranging interviews with campaign workers and officials and is short of staff. In addition to him, there is only one other investigator.

McIntyre has also been assigned by the board to investigate possibly conflict of interest on the part of suspended D.C. Department of Human Resources Director Joseph P. Yeldell in the awarding of some DHR contracts and leases.

In addition, McIntyre has been told to expand his inquiry into the mayor's 1974 campaign to include a report in The Washington Post that the mayor and top campaign officials paid a $5,400 debt for campaign-related expenses that were not reported.

Some persons on the three-member board have been consistently disappointed with McIntyre's work and are now seeking to get two more staff persons who might aid in the investigations, board sources said.

McIntyre's first report on the campaign was given to the board at a closed door meeting last Thursday. It recommended that no further investigating be done because the persons talked to up to that point had given no indiction tthat secret cash payments had been made.

The board has authority of impose civil penalties for violation of the city's campaign finance law and, in the event that criminal wrong-doing is found, can make recommendations to the U.S. Attorney's Office here.

Criminal penalties for illegal campaign contributions include up to six months in jail, a fine of up to $5,000 or both. There is also a criminal penalty of up to five years in jail, a fine of no more than $10,000 or both for knowingly filing false campaign reports.

There is a three-year general statute of limitations on campaign law violations. Thus, any civil or criminal charges stemming from the alleged cash payments would have to be made in the next five months.

McIntyre, a Republican who worked in the D.C. Corporation Counsel's Office for 24 years, was appointed to the campaign finance director's post by Mayor Washington in 1974.