Federal authorities are investigating a suspected embezzlement of potentially millions of dollars from a St. Louis area medical practice, according to a source close to the investigation.

The FBI and U.S. attorney's investigation comes on the heels of the termination by Metropolitan Urological Specialists PC of Dunard Morris, who until recently served as its chief executive. The investigation focuses in part on whether money was diverted from the firm's bank loans, the source said. The amount of missing money isn't known but could be millions, the source said.

The medical practice also maintains that Morris subleased a $5,475-a-month luxury apartment using company funds without approval of the firm's board of directors.

During the last two years, the company has shown signs of cash flow problems, including the buildup of about $1.3 million in delinquent federal, state and local taxes, interest and fees, St. Louis County records show.

Asked about the federal investigation, U.S. Attorney Richard Callahan said Thursday, "I don't want to prejudge anything, but it is a matter that has our interest."

Morris did not return phone calls Thursday. One of his lawyers, Patrick Smith at DLA Piper law firm in New York, has declined to comment. "I'm not authorized to talk with you," he said. Morris' local counsel, Richard Sindel, declined to comment.

Metropolitan's attorney, Mayer Klein, said the medical firm "terminated" Morris in mid-September but would not detail why. He did confirm that the company is investigating the missing money.

"There were some concerns with regard to prior management, and we're working with everyone involved … to ascertain the full and complete picture," Klein said. "I don't think anyone has ascertained at this time the extent of what is missing."

Patients should have no concerns about the company's overall finances or its ability to dispense medical care, he said.

"The company is doing very well. It's very solid. In fact, it's thriving," Klein said. "There was a problem that is being looked into, and we're working with the authorities. But we're a very strong company, so that problem will not affect any of our operations."

Metropolitan, whose practice includes radiation treatments for prostate cancer, has about a dozen physicians on its staff. It operates a sexual health clinic and offers surgical services. The Chesterfield-based firm has an imaging center, a laboratory and doctors' offices in Crestwood, Creve Coeur, Florissant and Chesterfield, including offices on the campuses of Mercy Hospital St. Louis and St. Luke's Hospital.

The firm was sued recently by Chesterfield-based VIP Corporate Housing in St. Louis County Circuit Court. According to the lawsuit, Metropolitan began renting a $5,475-a-month furnished luxury apartment at the Mansions on the Plaza complex at 8300 Delmar Boulevard on or about March 22 to house Morris, then its chief executive. But the medical firm fell behind on its rental payments in late September — about the time that Morris left Metropolitan. VIP Corporate Housing did not return a call for comment.

According to the Mansions website, its apartments have balconies, cathedral ceilings, granite countertops, stone/gas fireplaces and "oversized garden bathtubs." Its common areas feature an executive conference and dining room, a business center, a library, a screening room, a java bar and cyber cafe, a resort-style pool and fitness center, and a cigar lounge with billiards and board games. Its apartments range in size from one to three bedrooms, with various floor plans from 826 square feet to 2,477 square feet. The size of Morris' apartment is unclear.

"The matter is in litigation, but the company does not accept this as its lease. This was not entered into by the company," Klein said.

According to the sublease, the one-year agreement was signed by Allison M. Hancock, former operations manager at Metropolitan Urological Specialists, on behalf of the medical firm and Morris. Hancock used a credit card to pay for the apartment. Hancock, who left the company recently, did not return calls seeking comment.

Metropolitan's new interim chief executive, Bob Lawson, has declined to be interviewed about the medical firm's finances. Several of Metropolitan's doctors, some of whom serve as officers and board members of the company, have not returned calls seeking comment.

Klein has said that in recent months, the medical firm has paid down significantly its federal and state tax obligations. However, the firm's property affiliate — Metropolitan Urological Properties LLC — also owes more than $338,000 in delinquent property taxes, interest and penalties to state and local tax authorities on two of its parcels in St. Louis County.

On Sept. 16, the Internal Revenue Service filed an $855,291 tax lien on all property belonging to the Chesterfield-based medical practice as well as all of its property rights, federal records show. The IRS filed the tax lien after Metropolitan fell behind on some of its federal taxes — namely, the employer's quarterly payments of money that were withheld from its employees' paychecks.

Earlier this year, the Missouri Department of Revenue placed three tax liens on the firm totaling $154,103 involving overdue withholding taxes, state records show.

Since 2007, the medical firm and its property affiliate have obtained bank loans and lines of credit totaling more than $10 million. Metropolitan's board of directors approved various projects, including the construction of a new medical office building on Big Bend Boulevard in Crestwood, the purchase of a linear accelerator for radiation treatments and the build-out and remodeling of other facilities.

"Regardless of what Mr. Morris may have done, all the loans that we have on the books are authorized and are current. There are no defaults," Klein said. "The change of management has brought about a process to make sure that everything is being paid on time."