State officials said Thursday that lab tests back up their belief that raw milk from a dairy farm in Gibbon, Minn., is behind an outbreak of E. coli-related illnesses that have sickened at least five Minnesotans, including a new case they disclosed.

The strain of E. coli O157:H7 that showed up in all of the ill patients matched multiple animals and sites at Hartmann Dairy, according to the state's Health and Agriculture Departments.

They said a child in the metro area was the fifth person linked to the outbreak, while a toddler who had been hospitalized was released Wednesday.

"This is an ongoing investigation," said Nicole Neeser, program manager for dairy, meat and poultry inspection at the Minnesota Department of Agriculture. She said that if action is pursued, it could lead to criminal and civil penalties.

Officials said they are looking into several additional illnesses that may be connected to the farm's products.

The outbreak has highlighted a controversy over raw milk, which doesn't undergo the usual pasteurization process to kill organisms that can make people sick. Health authorities recommend avoiding the stuff, but there's a growing movement of advocates who believe it has health benefits.

Several of Hartmann Dairy's customers said earlier this week that they're not deterred by the E. coli outbreak and have doubts about the state's linking of the dairy to it.

Michael Hartmann, the farm's owner, said Thursday afternoon that he had not yet seen the state's statement on the evidence found. "I really can't make a comment on that," Hartmann said.

Health officials said they first discovered the E. coli outbreak through reports from health care providers. They looked into the illnesses, which were scattered across the state, and determined that the only thing the ill people had in common was consumption of dairy products from the Hartmann farm.

That led them to test the farm, where they said they found the same strain as in the ill people. Cheese samples they collected contained another form of E. coli, demonstrating that "an ongoing pathway of contamination existed on the farm," according to a statement health officials released Thursday.

The Minnesota Department of Agriculture said it has embargoed products on the Hartmann farm, stopping the release of products off the farm.

Laws on raw milk sales vary from state to state, with Minnesota allowing "occasional sales" at the farm where it is produced. Consumers are supposed to bring their own containers, according to regulators.

"Raw milk presents a serious health risk," Minnesota Health Commissioner Dr. Sanne Magnan said. "This risk isn't a matter of personal opinion; it's an established scientific fact."

Magnan said drinking or consuming raw milk products could expose consumers to organisms that can cause anything from a few days of diarrhea to kidney failure to death. Magnan said it can be especially dangerous for children to consume raw milk because their immune systems can't fight off the infection as well as healthy adults can.

The five people whose illnesses have been tied to raw milk products linked to Hartmann's farm include the toddler and the new case described as a "young child," two school-aged children and a 79-year-old person. The latest person to fall ill, the young child, was not hospitalized, officials said.

Wendy Lee • 612-673-1712