The Prince George's County state's attorney has begun an investigation into allegations that jail trusties performed personal chores for County Sheriff Don Edward Ansell and attended an unofficial banquet last year honoring one of his deputies.

State's Attorney Arthur A. Marshall Jr. said yesterday he has assigned an investigator to the case. "The chances are reasonably good," he said, that a new grand jury to be impaneled next week will become involved in the inquiry.

The investigation stems, Marshall said, from reports in Monday's Washington Post concerning Ansell's conduct in office.

The Post article quoted a former jail trusty who said he and another prisoner helped deliver food from the county jail to the deputy-of-the-year banquet at the Sheraton-Lanham last September and remained there for several hours. The article quoted Ansell as saying he had no knowledge of the trusties' participation or presence at the affair, he said he would document the receipts and expenditures for the banquet only "to a grand jury."

Ansell Marshall said yesterday, phoned the prosecutor in charge of the grand jury on Monday and offered to appear "without a summons" and waive his immunity from prosecution.

Marshall said he also is concerned about an allegation - attributed in The Post article to Ansell's brother-in-law - that trusties performed chores at the sheriff's house several miles from the Upper Marlboro jail. Ansell has flatly denied the allegation.

"I don't think that the authority of the court directing the sheriff to take custody (of prisoners) allows them to work for private affairs," Marshall said. "I don't think it was ever the court's intention to have the sheriff use trusties for personal use."

If either or both incidents are true, Marshall said, they could constitute the common law crime of malfeasance in office. The crime, a misdeameanor, has a one-year statute of limitations, he noted.

Marshall added, "however, that there may be other things we ought to look into," that would not be affected by the one-year time limit.