The mystery surrounding credit union funds linked to the Pittsburgh police chief’s office deepened Tuesday with the mayor revealing there could be five or more such accounts, the FBI starting to contact merchants and the deputy police chief saying a credit card was issued in his name without his knowledge.

“There may be more accounts than any of us even know about, and that’s what we’re trying to figure out,” Mayor Luke Ravenstahl said at a public appearance.

Police Deputy Chief Paul Donaldson said that while his name was not on any of the credit union accounts being scrutinized by the FBI and IRS, he was surprised to learn that a credit card — or possibly a debit card — affiliated with one of the accounts existed in his name.

“I was informed by the investigators that there were multiple credit cards issued and my name is on one of those, but I have no knowledge of it, and they verified for me that it was never used,” Deputy Chief Donaldson said Tuesday evening. “I said, ‘Wow, that’s news to me.’ “

The deputy chief said he did not know who the other people were with cards in their names or even if they were members of the police bureau.

Over the past week federal investigators serving subpoenas have taken paperwork from both police headquarters on the North Side and the Greater Pittsburgh Police Federal Credit Union in the West End as part of what appears to be a probe of the bureau’s special events and personnel and finance offices.

Neither the FBI nor the IRS has publicly explained what is being investigated, although Deputy Chief Donaldson has said he believes the inquiry is in response to internal allegations of misappropriation of funds from the offices.

Some of the agents’ interest seems to be in expenses charged to at least one of the credit union accounts listed as “Special Events c/o Sandy Ganster.” Ms. Ganster is manager of the bureau’s personnel and finance department. Special events is the police office that handles scheduling officers for off-duty work.

Records from the account show that on May 15, 2010, someone used a Visa debit card to make a $47.08 purchase from Bistro Francais, a late-night restaurant in Washington, D.C.’s Georgetown neighborhood.

The restaurant’s general manager, Pon Sothana, said an FBI agent contacted the bistro Tuesday afternoon seeking information about the transaction. Employees could find no record of it, although they did find documents from other purchases that month.

FBI spokeswoman Kelly Kochamba could not be reached for comment.

Documents obtained by the Pittsburgh Post-Gazette show various purchases locally and in other states made using the special events account — which had a Visa debit card associated with it — and another account listed as “I.P.F.” with an address of police headquarters.

Deputy Chief Donaldson said he did not know what the expenses were for, whether they were associated with the police bureau, or whether they corresponded to any business trips.

City Controller Michael Lamb, who is running for mayor, has said there are 15 authorized depositories for city funds and the credit union is not one of them.

Mr. Lamb said any diversion of city funds to the credit union account would be the equivalent of theft.

No one in city government or the police bureau has explained the existence of the accounts (at least one of which solicitor Daniel Regan said was operating in 2004), their connection to the chief’s office, the reason for the expenditures, who made them or the source of the funds.

Former Pittsburgh police Chief Robert W. McNeilly Jr., who ran the police bureau through 2005, confirmed that the FBI contacted him Tuesday morning and asked to speak with him about the credit union accounts. They are planning to meet this afternoon.

“I welcome the investigation,” said Chief McNeilly, who is head of the Elizabeth Township police. “The way people are saying now [one account opened] in 2004, I’d like to know what happened.”

Chief McNeilly has said he had no knowledge of the credit union funds.

The Post-Gazette has learned that at least one check for $5,675.52 from the University of Pittsburgh to the police bureau was deposited in September 2009 into the “I.P.F.” account.

Jerome Cochran, Pitt’s executive vice chancellor and general counsel, said Tuesday night he did not know why the check ended up in the credit union account.

“I haven’t the foggiest idea. We sent the check to the City of Pittsburgh Bureau of Police at police headquarters on the North Side as requested. Once the check gets somewhere, what somebody does with it, I have no idea.”

Mr. Cochran said Pitt had contracted with city police to guard a mobile science lab that visits schools throughout Allegheny County.

“The police department … billed us for that, sent us an invoice, the invoice was processed through accounts payable … and a check was written to pay the invoice,” he said.

How many other credit union accounts exist connected to the police bureau is not clear.

After a news conference Tuesday morning in Market Square to discuss Pittsburgh’s marathon, Mr. Ravenstahl said there are “hundreds if not thousands of expenditures” on accounts associated with the police bureau and maintained at the credit union.

“I know we’re talking about two, three, four, five of them now,” the mayor said regarding the number of accounts under review. “We want to do a thorough analysis and find out where the money was spent, was it appropriately spent, who used it, who had debit cards, and really get all those questions answered.”

Documents show that some of the money in those accounts was used to pay Giant Eagle expenses, airline fees, hotel rooms and restaurant bills in numerous cities.

Most businesses contacted by the Post-Gazette would not reveal who signed for the various meals and hotel rooms or knew nothing about the charges.

“I have no clue,” said Hai Hsieh, manager of Ming’s Restaurant in Washington, D.C., which is near FBI headquarters and the National Law Enforcement Officers Memorial. “There are so many policemen that come to our place.”

In response to various questions posed to the bureau’s top brass, Deputy Chief Donaldson said: “There is an ongoing investigation, which will address all of the questions that you have listed. Until the investigation is complete, I cannot respond to your inquiry. The bureau is cooperating with the FBI and has provided all pertinent documents.”

The credit union also is cooperating in the investigation. CEO Karen Janoski, who could not be reached for comment last week, sent a letter to the Post-Gazette that said the financial institution was subpoenaed to provide information for a grand jury investigation.

Federal agents sought “photocopies of account information for multiple named persons/accounts that are being investigated within the Pittsburgh police,” Ms. Janoski wrote.

Ms. Janoski also wrote that the FBI “told us not to discuss the subpoena with anyone. We were trying to comply with their request.”

City solicitor Daniel Regan has said the subpoena served on police headquarters last week was linked to a federal grand jury investigation. A federal grand jury is investigating a company founded by a former friend of Chief Harper, and Mr. Ravenstahl has said that he knows of no other current federal grand jury investigation.

Councilwoman Theresa Kail-Smith, head of the public safety committee, said news that a check written out to the city had ended up in a credit union account troubled her.

She said the apparent diversion of the funds raised questions about how the city was keeping tabs on its money.

“I do think that we have a responsibility to make sure that any public dollars are tracked appropriately,” she said. “I think we need to see what measures were put into place prior and what measures need to be put into place.”