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 that her parents blamed on “caffeine toxicity” after she drank two Monster Energy drinks in a 24-hour period.

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 in a press conference that their examination of Fournier’s medical records found no evidence that the drinks, or the caffeine in them, contributed to her death, 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 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 Fournier’s family, 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 received incident reports of five deaths that mentioned Monster’s namesake drink.

FDA spokeswoman Shelly Burgess said on Monday that the FDA “continues to look into cases in which energy drinks were suspected as a possible cause of death,” though she notes that the reports do not establish causality between the drinks and death.

“If we find additional information that establishes causality, FDA will take appropriate steps to protect the public and remove the harm,” Burgess said.