Maryland's top federal prosecutor defended the decision not to bring charges against any Baltimore area police officers in an FBI investigation of alleged moonlighting violations, saying yesterday there was no evidence that the off-duty officers were paid for work they didn't do.

U.S. Attorney Thomas M. DiBiagio said that court records filed by prosecutors in his office Friday incorrectly stated that more than 39 off-duty officers were paid by Staples Inc. for security work they never performed and wrongly referred to the officers as "ghost" employees of the office supply chain.

In an interview, DiBiagio said that the two-year investigation turned up no such evidence. He said the inaccurate information filed in U.S. District Court in Baltimore was a paperwork mistake: "It was an error on our part," he said.

The allegations became public Friday with the guilty plea of the lone defendant in the case. Michael Hollander, 37, a former loss prevention manager with Staples, pleaded guilty to one count of mail fraud and in court admitted his role in a moonlighting scheme that cost the company more than $348,000.

In open court and in papers filed that afternoon, Assistant U.S. Attorney Christine Manuelian described the scheme as one in which officers were hired and paid to provide extra security for area Staples stores, but never required to report to work. The allegations were spelled out in detail in the government's plea agreement with Hollander, which was originally drafted and signed in July by assistant prosecutor Barbara S. Sale.

DiBiagio said that document should have been updated to reflect that the allegations against the officers were not proven in the investigation. But he said the underlying mail fraud charge, accusing Hollander of falsifying Staples financial books, was unaffected.

Gary A. Ticknor of Baltimore, an attorney for Hollander, could not be reached yesterday for comment.

Last week, Ticknor called the plea agreement a good resolution for his client, even if prosecutors determined they could not bring any other charges in the case. He also said the government would have faced a difficult task in bringing charges against the officers involved.

Many of the officers had said, through their attorneys, that they did report to work for Staples - patrolling store parking lots, for instance, even if they did not punch a time clock, Ticknor said.

The long-running case had frustrated police officials in Baltimore and Baltimore County as well as union leaders, who had expressed concerns that it had tainted their ranks without any criminal charges being filed. The case also spotlighted a rare split between local FBI officials and federal prosecutors.

After the U.S. attorney's office announced in February that it would not pursue charges, FBI agents in Baltimore appealed to federal prosecutors in Boston to take on the case. Prosecutors there could have claimed jurisdiction over the case because Staples is based in Framingham, Mass. They declined.