Two cans of Monster energy drink are shown in this photo illustration in Los Angeles on October 23, 2012. (REUTERS/Sam Mircovich)

Monster Beverage Corp, defending its Monster Energy drinks from mounting criticism about potential health risks, said on Monday its medical investigators found no evidence that the drinks caused the death of a 14-year-old girl.

The family of Maryland teenager Anais Fournier sued the company last year after she died of cardiac arrest her parents blamed on “caffeine toxicity” after she drank two Monster Energy drinks on consecutive days.

Monster, the top-selling U.S. energy drink, has come under fire from U.S. regulators and politicians. On Tuesday, a Chicago committee on health and environmental protection will discuss an official’s proposal to limit the sale of energy drinks.

On Monday, Monster’s lawyer and two doctors it hired said their examination of Fournier’s medical records found no evidence that the drinks killed the girl, noting that she had been receiving treatment for a heart condition since childhood.

“’Why did she suddenly die’ is the question,” one of the doctors, California emergency room physician Michael Forman, said. “That question can never be answered with any certainty.”

Monster said on Monday that its team found “no medical, scientific or factual evidence to support the Maryland Medical Examiner’s report of ‘caffeine toxicity’.”

Forman said that given Fournier’s health history, she might have suffered cardiac arrest that day, regardless of what she drank. In addition, he noted that no blood test was ever taken to prove caffeine toxicity.

Kevin Goldberg, a lawyer for the Fourniers, told Reuters there were other symptoms of caffeine toxicity, though he declined to elaborate.

“We have our experts and they have their experts,” Goldberg said, adding that it was “not appropriate ... to litigate the case in the media.”

Energy drinks are caffeinated beverages with aggressive-sounding names like Monster, Red Bull, Rockstar, Amp and Full Throttle. They are often associated with active or extreme sports, which makes them popular with young men.

In addition to the Fournier lawsuit, the U.S. Food and Drug Administration said in October that it was investigating reports of five deaths that might have been associated with Monster’s namesake drink.

Monster shares were down 80 cents, or 1.6 percent at $49.86 on the Nasdaq.