You could call it a real whodunit.

Wells Fargo & Co. filed a federal lawsuit Tuesday in Minneapolis alleging that its trademarks are being used by an unknown group in violation of the Racketeer Influenced and Corrupt Organization Act (RICO). The suit says that "John Does 1-10," and possibly more, appear to be trying to convince investors that they have large amounts of money in Wells Fargo accounts, and that the money is available for financing and investing.

In fact, the accounts are "entirely fictitious," says the San Francisco-based bank.

It's not known how many people are victims of the scam, according to the bank.

"There is an ongoing investigation and we do have federal involvement in the process of identifying several individuals" involved in the alleged scheme, said Felicia Boyd, an attorney with Barnes and Thornburg in Minneapolis who filed the lawsuit.

Bank officials began getting complaints last year about a phony letter that appears to be from a Wells Fargo branch in Los Angeles. It asserts that an individual in Renton, Wash., had $100 million on deposit and notes that the money is free of encumbrances and was derived from "non-criminal" sources.

Letter to Detroit Lakes branch

In March, an unknown individual presented a similar letter to a Wells Fargo branch in Detroit Lakes, Minn., seeking to verify the existence of $905,372,077.33 in an account at the same Los Angeles branch. Similar to the other letter, it says that "these funds are legally earned, good clean and cleared funds of non-criminal origin."

Both letters, which were attached to the lawsuit, were purportedly signed by branch manager Tigran Sargisya. They list a phone number for verification purposes. While Sargisya is, in fact, a Wells Fargo employee, she did not sign or authorize the letter, the suit says.

The bogus phone number listed on the letter is a working number. Callers hear a recorded message that plays Wells Fargo music, states Sargisya's name and offers to take a message.

Wells Fargo said it traced the number to a private cell phone leased from a company called Reachme.com. The bank sent the firm a letter in October seeking suspension of the phone number and disclosure of the person behind it. But Reachme.com refused to comply "without compensation for the disclosure," the suit says.

Boyd said federal officials are investigating the matter, and she hopes to know more about the cell phone subscriber soon.

The letter submitted to the bank branch in Detroit Lakes appears to be addressed to two individuals associated with Makarizo International S.A. in Panama. That firm appears to be a fictitious entity that exists on paper only, Boyd said. The individual who presented the letter in Detroit Lakes also presented another letter that purports to authorize and authenticate the $905 million on account in Los Angeles. That letter was purportedly written by a director of Makarizo in Panama to Brite Business International Inc., which lists an address in Belize.

The suit charges trademark infringement, RICO violations and violations of the Minnesota deceptive trade practices and consumer fraud acts.

It seeks an injunction barring the defendants -- whoever they are -- from using the Wells Fargo marks and from competing with the bank. It seeks the destruction of any materials that use the Wells Fargo marks, plus triple damages, attorney fees and other undetermined damages.

Dan Browning • 612-673-4493