D.C. welfare investigators have found that 58 out of 60 federal Health, Education and Welfare employees receiving welfare from the city are either being overpaid or are ineligible for any assistance.

The findings follow a review of the first group of 142 cases of HEW employees who were recently discovered to be also receiving welfare under the Aid to Families with Dependent Children program. This program has provisions allowing low-income mothers who work to receive welfare supplementing their salaires.

City officials are also reviewing the eligibility of some 1,148 D.C. employees who are receiving welfare. The high rate of ineligibility or overpayment discovered in the first group of cases, however, prompted city welfare director Albert P. Russo to acknowledge at a City Council budget hearing yesterday that "serious questions" have arisen about the eligibility of the other federal and city employees.

Russo said investigators for his department will continue reviewing cases and turn those that appear to be fraudulent over to the city's corporation counsel for prosecution.

Russo said that of the 60 cases reviewed, 33 were found to be ineligible to receive AFDC and 25 were found to be receiving overpayments.

Those 58 HEW employees have been advised that their payments will be terminated or reduced and have been given 15 days to respond, Russo said.

In addition, Russo said, 13 Maryland and Virginia residents found, through a separate checking system, to be receiving welfare payments from the District, have been told their payments will be terminated. Those cases will also be reviewed for further legal action, he said.

Russo's findings are the result of a program called Project Match, which compares city and federal government employee rosters with welfare rools, Russo said he expects HEW Secretary Joseph A. Califano to send him the names of 1,570 other federal employee on the District's welfare rools.

Efforts to ease the financial burden on welfare recipients included hiring many of the mothers as clerks, typists and day-care workers, which Russo said explains to some extend the number of welfare recipients on the government payroll.

Russo's assistants attempted to make clear yesterday that just because a case review indicates that a person is being overpaid or is ineligible for assistance, it does not mean that a fraud has been committed.

Persons receiving assistance "could inadvertantly" fail to notify the city of a change in family situation that could affect payment or a change in address of a family member that could cancel payments for that person, one of Russo's administrators said.

"A father could return to his family or a child could leave the family to go live with someone else, say a grandmother. We have found some cases like these and sometimes you're hardpressed to say whether something was done, to deliberately mislead" the official said.

Those persons found to be ineligible for assistance came from a variety of financial backgrounds - "not all were poor; some made pretty money," one official said.

Some residents, however, use rather eloborate schemes to willfully defraud and cheat the welfare system, some investigators said.

Having moved from the city, some persons continue to receive District welfare checks by meeting the mailman every "Mother's Day," slang for welfare-check day, at the house where the person used to live.

Investigators have found that some welfare recipients use as a home address that of friends or relatives in the city. Investigators are prohibited by law from making unannounced checks on applicants.

"All they have to do is wait for the call (from the investigator), then go out behind some high school and find them a couple of children for a day," one official said.