Two top officials of the D.C. Department of Human Services were subpoenaed last week to appear before or provide documents to a federal grand jury in connection with a seven-month investigation into contracting practices by the city agency that runs the government's juvenile institutions.

Subpoenaed were Audrey Rowe, D.C. commissioner of social services, of which the Youth Services Administration is a part, and David E. Rivers, director of the Department of Human Services.

Rowe was asked to appear before the grand jury early next month.

About a dozen others, including Youth Services Administrator Patricia Quann, are expected to receive subpoenas this week as part of the investigation by the U.S. attorney's office, FBI and General Accounting Office.

"Audrey was asked to testify," said DHS spokesman Charles Seigel. "David Rivers was asked only to submit a complete set of certain documents."

Seigel said the documents include time sheets for Youth Services Administration employes. Rivers already has supplied the documents to the U.S. attorney's office, Seigel said.

Law enforcement officials said they are looking into overtime payments made to city employes who work in the youth agency offices, which are located in the Receiving Home for Children in Northeast Washington.

The investigation also centers on the agency's dealings with contractors and whether city officials or staff members altered or withheld documents subpoenaed earlier by the grand jury. Federal investigators said recently they had found discrepancies when comparing the agency's in-house records with copies of the records they received last year.

The probe began last fall after congressional hearings questioned whether the city violated federal laws concerning special education of children held in the District institutions.

Following the hearings, the U.S. attorney's office began looking into possible mismanagement of contracts awarded to Educational Support Systems, a District firm that assesses children's educational ability for the agency. An attorney for the firm has said all proper procedures were followed in its city contracts.

The investigation has been expanded to include all contractors doing work for the youth agency, including firms that operate group homes and that supervise delinquent children who are living at home.

Mayor Marion Barry was briefed on the investigation last week, according to Seigel.

The Youth Services Administration investigation is one of several recent federal probes into the contracting practices of the District government.

Other investigations have involved the city's Department of Employment Services, the D.C. Lottery Board and the Office of the Deputy Mayor for Finance.