When I went to Copiapo to find out how Chile's famous miners were faring one year after their dramatic rescue, I was amazed at the things that they refused to talk about: exactly how much food did they have during those first 17 days after the mine collapsed? What were the relationships like between them as they waited to be rescued? Is it true that one miner received illegal drugs?
The reason for all the mystery, I was told, was that the lawyer who was handling negotiations for a book and Hollywood movie deal had told them that they could not spill the beans about what happened down under, or the deal would be off.
Some of the things they would not discuss were in fact already common knowledge, such as how much food they had to survive on - two teaspoons of tuna, a biscuit and half a cup of watered down condensed milk every two days.
It was almost touching how they tried to protect their secrets. But not all of the miners were so determined to keep their promise.
When 33 men make an agreement 700 metres under ground, you can bet more than one will later be coaxed - or paid enough - to break it. And what is worse, some have been saying things that are not true, according to the miners I spoke to.
Victor Zamora, for example, told the US television programme 60 Minutes that during the first 17 days, before they were discovered alive, not only himself but the whole group had talked about committing mass suicide, rather than wait to die a slow death.
Many of the miners were outraged by the statement. "It is absolutely not true", said Omar Reygadas. "As a group we were betting on life, not on death. I never lost hope that God would help us and that we would be found and I was not the only one. Keeping our faith was the only way to keep sane."
Another subject about which many people in Chile speculated was whether the trapped miners had agreed to resort to cannibalism if all else failed. Chileans recall a precedent: the survivors of a plane that crashed in the Andes in 1972, which became the basis for the film Alive.
Mario Sepulveda, the miner with perhaps the highest media profile - nicknamed Super Mario for all his hyperactive jumping and chanting - said in an interview that he was willing to do it and that it was an option agreed upon by the group.
But when I ask several others if this was so, I was told that it was rubbish that while many may have contemplated it, the miners would merely joke about it to release tension.
"For example, when we started losing weight, we would tell the thinnest one: 'You don't even have enough on your bones for a meatball!' Or we would tell the fattest one, 'Hey, you'll make a juicy steak!' It was never seriously debated," I was told.
Presumably the truth about these and scores of other stories that have circulated will out when their story finally makes it to the silver screen. The miners told me that the contents of their movie must be agreed upon by all of them.
But one can only wonder. Hollywood does have a talent for turning fact into fiction - even a story which is already so extraordinary!
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