The former top auditor for the Prince William County government has been accused of stealing more than $30,000.

The victim? A D.C.-based association of auditors.

Robin Howard — who once headed the Prince William office intended to ferret out financial mismanagement — was indicted this week on six counts of embezzlement. A judge issued a warrant for his arrest.

Larry Keller, a former colleague, said that Howard had done “a lot of good” for Prince William and that he found it difficult to believe the charges.

“He knows so much about how you get evidence, internal controls, records,” Keller said. “It seems so unlikely that someone so knowledgeable could expect to get away with that.”

Howard served as director of audit services in Prince William until January 2012. He also served as treasurer and then president of the D.C. chapter of the Institute of Internal Auditors, an international association that sets standards for people whose job it is to prevent or detect financial fraud.

The association discovered something odd last summer, officials said: Bank records and financial reports did not match up. The bank reports had been going directly to Howard, but when he left the chapter and moved to Atlanta to work for the Metropolitan Atlanta Rapid Transit Authority, they were sent to board members instead.

They hired a forensic accounting firm to investigate and then turned the results over to police.

Howard declined to comment on the charges.

The local chapter of the auditors association is an all-volunteer group with 1,500 members. It typically kept between $30,000 and $70,000 in its accounts at any given time, said Kevin Mayeux, the chief operating officer of the overall group. About $50,000 is unaccounted for.

Howard had told the board that independent reviews of the chapter’s finances had been completed, Mayeux said, as is required by the organization. But the board has not been able to confirm that the review actually occurred. The alleged misappropriations took place between 2009 and 2012. Mayeux said the chapter is able to continue operating as before, offering professional development, training events and other services.

Prince William County officials were notified late last year that Howard was being investigated, said Corey Stewart, chairman of the Board of County Supervisors. County officials hired an outside auditing firm to check the books. When they got the report in February, he said, “we were happy to breathe a sigh of relief that, at least as far as the county was concerned, there was no missing funding or anything that the auditing firm detected.”

Howard resigned this week from his job as assistant general manager for internal audit at MARTA in Atlanta, according to spokesman Lyle Harris. The transit authority is reviewing its hiring process — and its books. “We’re looking at his tenure as a matter of course,” Harris said. “We don’t have any reason to suspect there is an issue.”

Howard had about $24,000 in child-support judgments against him, according to Fairfax County Circuit Court documents.

Howard was well respected in the field, a couple of former colleagues said, and gave talks such as “Five Critical Audit Tools for Managing an Effective and Efficient Audit Department.”

Stewart (R-At Large) said his first reaction was “absolute shock.”

“I just couldn’t believe it,” he said.

How could this happen to auditors?

“The chapter fell victim to trust,” Mayeux said.

Jennifer Jenkins, Jeremy Borden and Sarah Lane contributed to this report.