For the doctors at the Rocky Mountain Poison and Drug Center, the 11-month-old’s deathwas a puzzle.

He had been largely healthy for most of his young life, but his autopsy revealed that he died of myocarditis, an inflammation of the heart muscle that is rare in a child so young. Making the condition even more puzzling, doctors tested for — and ruled out — the most common causes of myocarditis, such as an infection or an allergic reaction.

That left one possibility in the doctors’ minds as the most likely answer to the puzzle, but it was a mystery, too. Tests revealed that there was THC, the psychoactive compound in marijuana, in the boy’s system. And, though the doctors had no information about how the THC got there or when, it best explained to them how the child developed a fatal heart condition.

“We’re not saying definitively that marijuana caused the myocarditis,” said Dr. Christopher Hoyte, one of two doctors who authored a now-controversial case report on the boy’s death. “All we are saying is we didn’t find any other reasons. So we need to study this further.”

Hoyte’s comments Friday shed new light on the boy’s death. Hoyte said the doctors at the Poison and Drug Center encountered the boy just before his death in 2015, not as a statistic for study but as a patient. The boy was brought to a hospital emergency room after suffering a seizure.

“It was just a normal working day,” he said. “We actually helped take care of the child.”

The boy’s heart rate at the hospital hit 156 beats per minute, then plunged to 40 beats per minute and then fell silent. Doctors attempted for an hour to resuscitate him before pronouncing him dead.

Hoyte did not disclose the boy’s name and said he could not identify the hospital where the boy was taken, out of privacy concerns. He said he did not know which city the boy lived in with his family — though the case report notes that the family lived in motels and that his parents admitted to drug possession. Hoyte said he did not know if law enforcement later investigated the case.

Hoyte said the THC detected in the boy’s system was enough to infer that he had consumed marijuana somehow and not just been exposed to it passively through secondhand smoke. But he said he never received more information that might explain how much marijuana the boy consumed. Toxicology tests led the doctors to conclude the boy’s marijuana exposure occurred two to six days before his death.

The case report, though published in March, exploded in the media this month, leading to online battles over whether the boy’s death was a marijuana “overdose” or an example of doctors wrongly blaming cannabis. Hoyte said the polarization took him and his co-author, Dr. Thomas Nappe, by surprise.

The medical research literature has dozens of examples in the past two decades from around the world of cases where doctors linked marijuana to heart troubles. That cannabis use can cause a rapid heart beat is unquestioned, Hoyte said. A 2001 study by doctors connected to Harvard Medical School found that the risk of a heart attack was nearly five times greater than normal in the hour after marijuana use.

But the literature is also quiet when it comes to explaining how, precisely, marijuana can cause heart problems, meaning the link between the two is still unclear.

“It is difficult to establish the cause-effect relationship between marijuana use and cardiovascular disease,” a case report published last year by doctors at the New York University School of Medicine stated.

But, later in that same case report, those doctors concluded, “Although uncommon, severe cardiovascular toxicity and death may develop from its consumption.”

Hoyte and Nappe’s report is not the first to link marijuana to a heart-related death or the first to link cannabis to myocarditis, specifically. (They do note, however, that the report is the first of a child death related to marijuana exposure.)

“We thought we were just saying were things that people would say, ‘Yeah, that makes total sense,’ ” Hoyte said.

And Hoyte said he now worries the online debate over whether marijuana can kill will overshadow the messages he and Nappe hoped the report would send. The first message, he said, is to remind parents to keep marijuana locked up so that kids can’t get it. The second is to call for more research into marijuana and heart health.

“The point is,” Hoyte said, “we just want to understand it better and study it.”