As CBS News correspondent Allen Pizzey reported on The Early Show Wednesday, the pope's slow demise was watched by hundreds of thousands who jammed St. Peter's Square, and by the rest of the world on TV.
The physician leveling the mercy killing allegation, Dr. Lina Pavanelli, heads the intensive care medical school at Italy's University of Ferrara.
"The doctors had done something, the doctors didn't inform the pope completely, or the pope decided," Pavanelli told CBS News. "These are the three conclusions that I reached."
She based her conclusions, Pizzey points out, on TV coverage, press reports, and a book by the pontiff's personal physician.
A feeding tube wasn't inserted into John Paul II until three days before he died, which Pavanelli charges was far too late.
One of the effects of the late stages of Parkinson's disease, which afflicted John Paul II for years, is an inability to swallow.
In her article, Pavanelli writes that, "I let my perceptions conform to the hope of recovery and the official version, without confronting the clinical signs that I was seeing."
John Paul II's successor, Benedict XVI, recently issued a document denouncing cutting off food and water to patients in a vegetative state.
The Vatican took that stance in the case of Terri Schiavo, the severely brain-damaged American woman who was eventually taken off a feeding tube and died. The Vatican ruled that, "The administration of food and water, even by artificial means is, in principle, an ordinary way of preserving life."
The Vatican also ran into controversy when it refused to grant a church funeral for an Italian man who successfully petitioned to be allowed to die after being on life support for nine years.
The euthanasia allegation will be almost impossible to prove, Pizzey says, not in the least because Dr. Pavanelli wasn't part of the pope's medical team.
All the Vatican will have to do, Pizzey adds, is point to John Paul II's insistence on suffering in public to show his belief that all life has value.
And Father Thomas Williams, a CBS News consultant and Catholic theologian based in Rome, dismisses Pavanelli's conclusions.
"I think," he told Early Show co-anchor Harry Smith Wednesday, "it (failing to insert the feeding tube for so long) was a medical decision. It could have been a good one or bad one. But euthanasia, remember, is the intentional acceleration of the death of a person. And, I think, to allege that they intentionally accelerated Pope John Paul's death is really farfetched. I don't think anyone wanted that -- not the pope himself, and not anyone who was close to him."
"I have spoken with a number of doctors, both ... in Italy and in the United States about this," Williams continued, "and there's no consensus there. Dr. Pavanelli is definitely in the minority in saying the tube should have been inserted earlier. In fact, the tube is only put in when the patient is no longer able to ingest food and liquid by his or herself. And the pope was able to do that until shortly before his death."
Williams observed that, "Everybody loves a conspiracy theory, especially when it relates to the Catholic Church. I remember back in 1978, when Pope Paul VI died, everyone started putting forth theories that he was poisoned or killed in some way. The same thing happened after the death of John Paul I, so I'm not really surprised."
There's been no official Vatican reaction to Pavanelli's article yet and, "I don't think there will be, unless the reaction to this reaches a critical mass where the Vatican feels that it's obliged to make some sort of a statement," Williams says. "There has been an immediate statement by the pope's personal doctor ... who was there at the pope's bedside up to the point of his death. He said these allegations are simply false."