The court-appointed attorney for U.S. employee William Sibert said yesterday that his client wants to help the federal government account for the $856,000 he allegedly stole and spent in the last two months.

The unusual offer came after a federal prosecutor claimed at a bond hearing that the government still had not been able to account for approximately $200,000 of the missing funds, and therefore wanted a high bond set for Sibert.

Sibert said through his attroney, Ed Wilhite, that he could account for all but about $6,000 of the money, most of which Wilhite said essentially was "frittered away." Wilhite said Sibert was penniless now, with all his assets frozen by the government in civil actions.

Sibert, who has not entered a plea of guilty or innocent in the case yet, was ordered held on $50,000 bond pending his cooperation with the government. A review of that bond has been scheduled for Wednesday morning before U.S. Magistrate Henry H. Kennedy Jr.

Meanwhile yesterday, Assistant U.S. Attorney Robert W. Ogren disclosed that the 30-year-old Sibert - who allegedly stole the money while a GS-5 financial assistant at the U.S. Department of Transportation - had faced criminal charges twice in the past.

In 1966, Ogren said, Sibert was sentenced to eight years in prison in Maryland for housebreaking. Ogren said Sibert served nearly six years in prison for that offense.

Last year, Sibert was charged in U.S. court in Northern Virginia with a firearms violation, Ogren said. The charge was dropped when Sibert was placed in a pretrial diversion program on the promise that he would keep in regular touch with a probation officer, Ogren said.

Ogren said Sibert was supposed to notify his probation officer of any trips he took, but that Sibert had not told the probation officer about trips to Las Vegas and Miami and other "pleasure trips with stolen money."

Sibert was arrested more than a week ago in Las Vegas and more than $59,000 in cash was taken from him there by arresting agents. In addition, investigarors have been untangling a complicated web of financial transactions in which Sibert allegedly bought at least 14 luxury cars, a house with a swimming pool, and a topless bar, and other items.

Agents also have uncovered unusually large tips awarded by Sibert, including a $1,000 tip to a baby-sitter, they said.

"There's still money missing in the form of cash," Ogren told Magistrate Kennedy yesterday. "He has it stashed somewhere. To preclude the possibility this man could bail himself out with stolen money, we ask for a substantial bond."

Wilhite said that Sibert was attempting to account in his own mind for the amount of money he had spent.

"Mr. Sibert says he knows of no great sums of money. He believes he is able to account for all of it but about $6,000," Wilhite said.

Wilhite continued, "Mr. Sibert is more than willing to account to the government for the money."

"That offer is too good to refuse," Ogren replied.