To many of the eclectic tenants in the historic building at 711 W. Lake St. in Minneapolis, Bella's Body Therapy was just a tiny, nondescript business doing its thing on the second floor.

But at least one of the building's tenants in the quiet and popular East Lowry Hill neighborhood grew suspicious when "sexual noises" began emanating through the shop's walls, and lots of men kept coming and going all day long.

So police went undercover, and according to a search warrant affidavit filed in Hennepin County District Court, found that Bella's "massages" always ended up with sex being offered for money. Sara Steffl, Bella's owner, said she was stunned when informed of the prostitution allegations during a search by police two weeks ago. On Wednesday, she denied any illegal activity at Bella's, but said she has fired employees when she discovered they were having sex with clients.

Marc Norberg, owner of a photography studio in the building, wasn't aware of what was happening at Bella's. The building is full of terrific tenants, including a writer, lawyer and a dance studio on his floor, he said.

"It's a building where everybody watches out for each other," he said. "I'm kind of embarrassed and angry at the same time. Somebody took advantage of the building's management. It's unacceptable."

Charges are pending and legal action against the property by the Hennepin County attorney's office is imminent, said Sgt. Matt Wente, one of the case's investigators. He said he has no doubt Bella's was in the prostitution business because undercover officers were offered sexual services by four different women on four different visits since July.

Bella's is one of at least 20 similar massage parlor businesses operating in the city's Fifth Precinct, which includes popular neighborhoods in south and southwest Minneapolis, said Precinct Inspector Kris Arneson. Police have been able to shut down several parlors, but the owners are making it more difficult for undercover officers to get "code words" needed before the women will offer up any services, she said.

The parlors often are low-key operations in busy retail districts, and Bella's was no exception. Beat cops have been working the area near the parlor's building at Lake Street and Aldrich Avenue S. since January, but it took a tenant to tip off police, Arneson said.

"I hadn't heard a word about what was going on at Bella's," said Awin Briem, owner of Art with a Point, a tattoo studio on the fifth floor. "I know most of the people in the building, but I guess you never know."

Wente and Sgt. Grant Snyder, who work for the department's Violent Offender Task Force, said as many as six women worked at Bella's. The officers who went undercover told Wente there were only two small rooms with massage tables in the office, and that the women made it immediately clear that "sex for money" was routine business practice. Some of the services cost $200 per hour.

"The tenants told us there was a steady clientele," Wente said.

When police searched the business March 19, they didn't find any items that would directly indicate Bella's was engaging in prostitution. But on the bottom of an employee application, somebody had written "nudity not a problem."

Steffl said the officers seemed surprised when they entered Bella's for the search. They asked her, "Where's the safe?" and took only several schedule planners and notebooks.

"At first they told us we were going to have to shut down for the day, but then they changed their minds," she said. "I didn't think it was a big deal. Why am I being targeted?"

Bella's has been at 711 W. Lake Street for about a year and a half, but Steffl said she has been in the massage therapy business for six years. Her employees have to show proof that they have taken massage classes and have to sign an agreement that they won't be involved in illegal activities, she said. Steffl said she went to massage school for two years.

"I don't tolerate any prostitution or drug use," she said. "We keep our front door open during the day."

When asked about the tenant who complained to police about "sex noises, " Steffl said that some of her employees might use elbows during deep tissue massages, and that clients may let out a moan.

David Chanen • 612-673-4465