The story of Sierra Leone's "hero doctor" does not have a happy ending.

Even though Dr. Sheik Umar Khan was an experienced virus warrior, and hemorrhagic fevers were his specialty, he tested positive for Ebola on July 22 and died in seven terrible days.

His friends and colleagues from around the world are sick with grief, and a haunting question hangs in the air. Did doctors make the right decision in refusing to treat him with an experimental drug?

It was an agonizing ethical drama that literally played out at his bedside, CBC discovered as we pieced this story together.

As the virus ravaged his body, doctors had a choice. Should Dr. Khan become the first human to receive an untested drug with unproven efficacy and unknown risk?

It was a question they could ask because of a simple quirk of fate. A single dose of the treatment happened to be within reach of that remote field hospital in rural Sierra Leone.

It was a lone sample of the drug called ZMapp, one of apparently only five in the world, brought by the Canadian scientists who helped develop it.

The Canadian team was testing the drug at a field laboratory near the border with Guinea simply to see how it would hold up in the African heat, according to a statement released by Doctors Without Borders.

When they offered it to the physicians treating Dr. Khan, they triggered an unprecedented philosophical debate that was argued across continents, as the virus wreaked its havoc on their colleague and friend.

The drug had never been tested on humans. What if it caused an allergic reaction that killed Dr. Khan?

His blood showed antibodies to the virus, evidence that his own immune system was already in full battle. What if the drug got in the way of that immune response?

But what if it worked?

But what if it worked and saved his life? And, what about all those other patients?

Was it ethical to give the drug to one person while so many others were dying without that option?

It was a debate that ricocheted between the bedside at the field hospital in Kailahun, in Sierra Leone's Eastern Province, to the Geneva offices of the World Health Organization, and the Belgium headquarters of Doctors Without Borders, according to Dr. Daniel Bausch, a long-time friend of Dr. Khan and a fellow virus warrior.

HEALTH-EBOLA/AFRICA/

Sheik Umar Khan, head doctor fighting the deadly tropical virus Ebola in Sierra Leone, poses for a picture in Freetown, June 25, 2014. Khan, a Sierra Leonean virologist credited with treating more than 100 Ebola victims, contracted the disease a month later and died on July 29. (Umaru Fofana / Reuters)

Just days earlier the two had been working side by side at the field hospital near the Guinea border, ground zero of the Ebola outbreak. Dr. Bausch left the day before Dr. Khan started feeling sick.

Worried about his friend, he weighed in on the debate from Geneva. "You had a person who was sick, and a drug never used on humans before, it wasn't approved. There were lots of questions to be asked and no easy answers," Dr. Bausch said.

Ultimately, he believes, the final decision was left with the doctors at the field hospital in Sierra Leone, although it was not a unanimous decision.

"There was, I don't want to say dissension," Bausch said. "But there were very definitely differences of opinion, and disagreements about what should happen."

The wrong call?

In the end, Dr. Khan did not get the drug. And for Dr. Bausch it was the wrong decision.

"I disagreed with what ultimately happened," he said. "I do want it to be clear that these were difficult, delicate decisions that people in a stressful situation had to make. But I'm not going to deny that I disagree with the decision they made."

Adding to the anguish, Dr. Khan never knew he had the option. No one told him about the experimental drug. No one asked this specialist for his own opinion about his choices, and whether he was willing to be a test case.

And that, for Dr. Bausch, was the biggest mistake.

"Dr. Khan was the ideal person to make an informed decision on this, and I feel strongly that he should have been asked if he wanted it or not," Dr. Bausch said. "That's one area where, frankly, I am critical."

In its statement about what happened in this case, Doctors Without Borders says Dr. Khan was not consulted about the experimental drug because, "ethically, it would be wrong to inform a patient of a potential course of treatment and then withdraw that option at a later stage."

Late in the night, at the Ebola treatment centre in Kailahun the doctors made the difficult call. The risks outweighed the benefits, at least at that moment.

The treatment, it was felt, if it was to be used at all, would be better attempted at the more sophisticated hospital in Europe where Dr. Khan was about to be moved.

But the next day his condition deteriorated, and he could not be transported after all. He died of Ebola a few days later on July 29.

Shocked the country

The very next day the drug was tried on humans for the first time when two U.S. aid workers infected with Ebola — a doctor, employed by the U.S. Christian charity Samaritan's Purse, and a missionary — were treated in neighbouring Liberia.

The unused Canadian dose that had been offered Dr. Khan was passed on to Samaritan’s Purse, according to a spokesperson from Health Canada on Monday.

They are now recovering in a hospital in Atlanta, Ga. A Spanish priest who also received the experimental treatment later died.

Back in Sierra Leone, Dr. Khan is remembered as a hero. A reporter there told me that Khan's death finally shocked the country into action.

"I personally think that helped to change the minds of the people to believe in the existence of Ebola.

"Before his death there were persistent denials about the existence of the Ebola virus disease," Amara Bangura, of BBC World Action said. "The ministry of health only stepped up the public education after the death of Dr. Khan. In fact that was when our president declared a state of emergency."

A few weeks before his death, Dr. Khan had told one of Bangura's colleagues that it was scary, working on the front lines of the epidemic.

"Yes, I'm afraid for my life. I must say I cherish my life, and if you are afraid of it you will take the maximum precautions," he said.

No one knows how he became infected. But the risk had long worried his brother. C. Ray Khan told CNN he begged Dr. Khan to come home and leave the fight to others.

Asked what he would say to his brother now, Khan replied, "Hey Umar, you didn't die in vain. You died for humanity."

With files from Amina Zafar