A worker at the Social Security Administration headquarters was charged today with manipulating the national computer at the complex in order to pay herself and two accomplices more than $500,000 in disability benefits.

The computer, in the Baltimore suburb of Woodlawn, sends out $1.1 billion in disability checks to 4.8 million workers and their dependents each month.

The Secret Service, which spent 18 months unsuccessfully trying to trace the money stolen through false disability claims, today described the computer theft scheme as "very, very sophisticated."

"If there hadn't been a bank official in Philadelphia alerted to a discrepancy in an account opened there, we'd still be operating in the land of the unknown," said Andrew E. Berger, head of the Secret Service office here.

"This was a very sophisticated scheme and the potential of the misuse [of the computer] and the lack of safeguards at Social Security is alarming. There's a potenital [that] we're sitting on the tip of an iceberg with this." He said agents from Washington, Philadelphia and California are continuing the investigation.

John Trollinger, a spokesman for Social Security, said, "There are safeguards in place and we are continuously reviewing and revising our computer system."

The worker is accused of processing disability checks under numerous aliases, using real social security numbers and then erasing all records of payments from the computer before it produced a regular audit of claims and payments, Berger said.

Berger said Janet Elizabeth Bartee Blair, 29, who has worked at the Agency since 1973, allegedly operated the computer theft scheme by filling out the paperwork for the computer to send disability checks to various addresses and post office boxes in Washington and Philadelphia. The two accomplices allegedly picked up the checks, cashed them through savings accounts with several banks, and a short time later, closed out the accounts, Berger said.

None of the money allegedly obtained from the scheme has been recovered, investigators said.

Blair was arrested at her Baltimore home today after calling in sick to her office. She is still employed at the Social Security Administration, and a spokesman there said Blair 'was "transferred to a nonsensitive position as a result of the investigation."

She was ordered jailed in lieu of $100,000 bond by a federal magistrate following her indictment on 43 counts of conspiracy to defraud, causing false Treasury checks to be made, and aiding and abetting forgery.

Stella Marie Abrams, 31, of Philadelphia, and Malcolm Blair, 29, Blair's brother-in-law, were charged as accomplices in the indictment returned by a federal grand jury here today. Malcolm Blair is currently serving time at Lewisburg federal penitentiary in Pennsylvania on an unrelated charge of receiving stolen Treasury checks.

Assistant U.S. Attorney David Queen said at the bail hearing for Janet Blair that she was "not acting alone" in the scheme and may have been taking orders from members of a religious sect.

Queen acknowledged that any suspicions about what happened to the half-million dollars allegedly stolen in the computer fraud scheme are just suspicions.