A three-year investigation into a salmonella outbreak has been traced to an unlicensed food processor dubbed "Mr. Cheese" who was making homemade "queso fresco" from raw milk, Utah public health officials said Thursday.

Some 73 cases of Salmonella Newport have been confirmed in six Wasatch Front counties since 2009, said Dr. Royal DeLegge, director of environmental health for the Salt Lake Valley Health Department.

Eleven cases were confirmed in 2009, followed by another 22 cases in 2010. As of Thursday, 40 cases had been confirmed this year.

But as many as 2,100 people may actually have had the infection, which causes nausea, stomach pain, diarrhea and fever. Some may have become ill after consuming the cheese, and others could have contracted the illness by having contact with infected persons.

"We estimate the number of people sickened is 30 times the number of reported cases," DeLegge said. "That's a lot, which is why we are so concerned about it."

Authorities said the soft, Mexican-style cheese was sold to at least one Salt Lake County restaurant and may also have been sold to individual consumers from the cheese-maker's car.

"We think he had a route," DeLegge said, who said the investigation was discussed during a health department board meeting Thursday.

"Mr. Cheese" was identified last summer by authorities after an investigator for the Salt Lake County district attorney's office showed a series of photographs to a restaurant owner.

In August, the Utah Department of Agriculture and Food issued a cease and desist order to the cheese-maker, who does not have a license to manufacture cheese, DeLegge said.

An investigation of the Salt Lake County man, whose name was not released, is ongoing, and he faces administrative fines, the agency's spokesman, Larry Lewis said.

Health officials believe the source of the contamination that triggered the salmonella may have been the raw milk used in the cheese production. Testing has been conducted at dairies in Wasatch County, although no specific source has yet been identified, Lewis said.