Federal investigators have uncovered a network of nearly 250 bank accounts that allegedly was part of an elaborate scheme in which some officials of Washington's Pride Inc., organizations stole, diverted or misappropriated hundreds of thousands of dollars from low-income tenants and the federal government, according to knowledgeable sources.

The accounts were found during a criminal probe into alleged financial misconduct by Pride executive director Mary Treadwell and some of her staff members.

Sources said the investigation, which began seven months ago, focuses on P. L. Properties, Inc., the Pride real estate spinoff that owned and operated Clifton Terrace Apartments.

Investigators are probing the alleged misuse of funds that should have been used to pay the mortgage, held by the U.S. Department of Housing and Urban Development, and other debts.

Pride or Pride Inc. is actually several organizations headed by Treadwell, including the 13-year old Youth Pride Inc., which has received some $21 million in federal job training funds, and several business spinoffs, including ventures in trashcan advertising, landscaping, painting, apartment management and housing rehabilitation.

The bank accounts being scrutinized in the probe reportedly show how money was sometimes shifted from organization to organization under the Pride umbrella, in an apparent attempt to hide the flow of money into accounts for personal use.

The investigation was launched last October after a series of articles in The Washington Post reported the theft or diversion of some $600,000 from Clifton Terrace by Treadwell, her sister Joan Booth, and former property manager Robert E. Lee Jr.

Treadwell has denied all wrong-doing, Lee declined to discuss specifics and Booth declined to be interviewed.

It is now known that the federal probe is also aimed at other business and personal associates of Treadwell, Booth and Lee.

For example, sources close to the investigation said the probe is examining the use of million of dollars in Labor Department funds given to Youth Pride, Inc., over the past decade for the job training of underprivileged black youths.

Another area of the investigation involves allegations of payoffs to government officials and local businessmen for assistance in covering up the alleged fraud scheme, sources said.

The investigation is one of the most massive ever conducted in the federal prosecutor's office here, and has become so large that the potential evidence from the scores of bank accounts is being computerized in a special office in the U.S. courthouse here, sources said.

At least seven FBI agents and three IRS investigators are working full time on the probe, which is expected to take at least another six months. One of the sheer volume of records involved, inclues tens of thousands of cancelled checks being reviewed, sources said.

U.S. Attorney Charles F. C. Ruff has refused to comment publicly on matters. He has reportedly told associates, however, that he considers it the "top priority" investigation in his office, even more important than the Abscam investigation.

By reviewing the documents, investigators have determined that government funds were comingled with private funds on some occasions and used to back business and real estate ventures benefiting some Pride leaders, according to sources with the investigation.

More than 50 persons have been interviewed by FBI agents and prosecutors and at least 200 grand jury subpoenas have been issued concerning the alleged fraud. Few persons have actually testified before the grand jury at this stage of the investigation, sources said. But the grand jury activity is expected to intensify this summer after the initial interviews are assessed and the records are catalogued further.

Because of strict new government privacy regulations limiting the cooperation of tax investigators in some types of criminal cases, it took several weeks before IRS investigators were allowed to work jointly with the FBI in the case. Now, however, those tax investigators are said to be playing a major role in the probe.

While the investigation has been shrouded in secrecy and plodding along at a slow pace that reportedly rankles the prosecutors themselves, there has been extensive speculation about it's status.

The investigation into Pride is believed to be the most massive ever into any of the 1960s Great Society social welfare programs.

Youth Pride was founded by Treadwell; Marion Barry, who is now mayor; Carroll Harvey, one of the mayor's top aides; and others. Barry was married to Treadwell from 1972 to 1977. He was not implicated in any wrongdoing in the Post series.

Those articles dealth with theft, misappropriation and diversion of funds by Treadwell, Booth and Lee when they ran P. I. Properties, Inc., which was a real estate spinoff of Youth Pride.

P. I. Properties owned and managed Cliford Terrace, a long-neglected 285-unit apartment complex at 14th and Clifton Sts. NW, between April 1974 and August 1978, when HUD foreclosed on the mortgage note it held.

At the time, P. I. Properties owed the federal government more than $400,000 in back mortgage playments and other loans, and owed the D.C. government

While tenants complained bitterly about lack of heat, power and trash collection during P. I. Properties' management of Clifton Terrace, officials of the firm used much of the $45,000 in monthly rental collections for their own personal use and business ventures, the Post reported.

Treadwell, Lee and Booth used tenants' money for financing a high-spending lifestyle, including improvements on their homes, a real estate speculation venture, Sticks and Stones, Inc., and a trip to a luxury resort in Jamaica.

Treadwell rented an expensive apartment at the Watergate, drove Mercedes and Jaguar sports cars and hosted catered parties at major hotels while running the Pride organizations.

Last week, she and a group of about 50 persons met at the Harambee House motel for a cocktail party that launched the "Mary Treadwell Legal Defense Fund." Treadwell claimed to have sold her Jaguar and put her Capitol Hill home up for sale, and she said her legal fees were nearing $80,000 -- more than she had the ability to pay.

The once-promising network of Pride spinoff organizations has recently fallen on hard times. Among them are Youth Pride Economic Enterprises, Inc., formed in 1968 to establish businesses that would provide jobs for trainees emerging from Youth Pride; Pride Environmental Services, Inc., formed in 1972 to provide the District of Columbia with 10,000 curbside trash cans; and T. Barry and Associates, Inc., set up to sell advertising on the trash cans.

All of these organizations are now defunct, but prosecutors are known to be examining the complex financial relationships among them.

Youth Pride, still headed by Treadwell, is currently receiving about $500,000 from the U.s. of Labor for job training programs.