Somewhere among his private documents, Italian media say there is a piece of paper that had the power to end John Paul II's papacy in a matter of moments.
The resignation letter - which Karol Wojtyla allegedly wrote as he struggled with diagnosed Parkinson's disease in recent years - was to be read only if he became mentally unfit to rule. It would have declared the Holy See vacant, ordering a conclave to elect a new pope.
In the end, such a letter was never needed. But as cardinals look ahead to next week's conclave to elect a new pope, a look back at the fragile condition of John Paul II's last years has persuaded more and more "red hats" that the Roman Catholic church must find an acceptable way for future ailing pontiffs to resign.
"There is a sense among the cardinals that they got lucky that John Paul II did not sink into a coma for a protracted period," says Vatican expert John Allen.
As one of the world's most vociferous pro-life voices, the Vatican supports the concept of using all available medical resources to keep people alive. John Paul II, nevertheless, chose not to be hospitalized in his final days.
Canon law makes no clear provision for the papacy to be vacated if a pope became mentally impaired.
"The general consensus now is that once his creative capacity has gone, in the future a pope will resign," Mr. Allen adds.
But it is far from clear how that can be technically done. Canon law is brief on the question of a papal resignation. Canon 332 states that a pope "makes the resignation freely and that it be duly manifested, but not that it be accepted by anyone." And Canon 187 asserts that "any person of sound mind can resign an ecclesiastical office for a just cause," suggesting a mentally impaired pope cannot make this decision.
"The real problem for the next papacy is that canon law just doesn't say much about what to do if a pope becomes mentally impeded," says the Rev. John Beal, a professor of canon law at the Catholic University of America, in Washington.
For centuries, resignation has been taboo. Popes are expected to remain in office until their death. Hence the adage: "A pope is never sick until he's dead."
Canon law does allow for resignation, but only a handful of popes have used the option, all because of power struggles - none because of failing health. The last to resign voluntarily was Celestine V in 1296, who was elected at 84 and resigned within a year, overwhelmed by the job. His decision was seen as so unsuitable that in the epic poem "Divine Comedy," Dante Alighieri placed him in hell.
But Vatican insiders say John Paul II's long struggle with illness has made the prospect no longer unthinkable.
In his last years he was unable to walk or speak clearly. Biographers say he worked only for a few hours each day, leaving all but essential Vatican decisions to a handful of his closest aides.
Some argue a pope does not need to be in charge of day-to-day affairs as long as he is a visible figurehead. Others say once he is reduced to cameo appearances, wheeled out for public events, it is time for him to go.
Already several key cardinals - from Godfried Danneels of Belgium to Mario Francesco Pompedda of Italy and Germany's Karl Lemann - have hinted that resignation should be considered.
Cardinal Jorge Mejia, the pope's longtime associate, said it would be "desirable and prudent" if the pope had drafted a resignation letter in case he became incapacitated.
John Paul II always insisted he would serve as long as God wanted. Yet his last testament, made public last week, revealed that in 2000, when he turned 80, he had considered stepping down.
But how does a pope retire if he is no longer able to speak? Should there be an informal understanding that a pope should step down at a certain age? Or should every pope prepare a resignation letter in advance?
Vatican officials insist - despite media reports - that John Paul II never wrote such a letter. Confirmation may only come from a member of his inner circle, such as private secretary Stanislaw Dziwisz.
In 2001, Bishop Pasquale Macchi, who had served as private secretary to Paul VI, revealed in a book that Paul VI had "prepared a letter of resignation to be delivered in case conditions occurred that would make it impossible to continue to govern the church in an adequate way."
Paul VI had also reportedly prepared a retirement retreat at the Benedictine Abbey of Montecassino. But neither this apartment nor the letter were needed, since Paul VI remained lucid until he died in 1978.
"Most probably, future popes will also write a resignation letter to provide a way out," says Marco Politi, one of Italy's leading Vatican experts. "Informally, this is the answer. It saves the doctors from having to intervene so the pope remains the ultimate judge."
But for many, the letter-in-a-drawer solution is not adequate.
"A letter is not enough," says Father Beal. "For a start, you would have to be sure of its authenticity - and of the mental state of the pope at the time of writing. Then you have to wonder whether those close to the pope might find it convenient not to use the letter."
Some say that it is time for a mandatory retirement age to be set.
"We live too long and people cannot continue to carry that responsibility if they they turn 90 or 100. It doesn't matter how well they are looked after," Cardinal Danneels told the Belgian magazine Knack in 2003. "But that the pope in the future will abdicate before his death is a matter of course."
But, as canon lawyers point out, even if a retirement age were set for popes at 80 - or 75 as it is for bishops - the pontiff, as the church's supreme judge, has the right to ignore the law.
In the past, progressive church leaders have asked publicly why bishops must resign at 75, while popes are deemed fit to serve "until their last breath." Cardinals, too, have wondered why they can't vote for a pope after they turn 80, even though popes can hold office for life.
Some argue that these days it should be mental state, not age, that determines eligibility both to vote or to be a pope. "It is a great deprivation for cardinals," Cardinal Giovanni Cheli told the Monitor before a ban on talking to the media was imposed.
At 86, Cheli, like 66 other cardinals past voting age, is watching this conclave from the sidelines. "Perhaps those whose minds have gone should not vote. We all know who they are. And some of them are in their seventies," he says.
Some popes have ruled and thrived well past 80, like Leo XIII who ruled actively, issuing encyclicals and intervening on social matters until he was 93.
Italian reports say John Paul II had ordered experts to study canon law to determine when a pope could retire. The study concluded that the only acceptable reason for a pontiff to abdicate was "amentia" - loss of mental capacities.
Any other reason, it noted, could rupture the church, dividing loyalty between the new pope and his predecessor.
As John Paul II himself once put it: "There is no place in the church for an emeritus pope."