Lead Masks Case

The Lead Masks Case (or rather splendidly in Portuguese, O Caso das Máscaras de Chumbo) was a mysterious event in 1966 when two Brazilian technicians were claimed to have been killed by aliens. Manoel Pereira da Cruz and Miguel José Viana were found dead on Vintém Hill in Rio de Janeiro, Brazil on August 20, 1966, by an 18-year-old man flying a kite; they were wearing formal suits, waterproof coats, and mysterious lead masks of an unclear purpose. Their bodies were partly covered in grass and there were wet towels nearby. There was no obvious cause of death, neither violence nor poisoning.

A notebook was also found, which included the message "16:30 estar no local determinado. 18:30 ingerir cápsulas, após efeito proteger metais aguardar sinal mascara" ("16:30 be at the specified location. 18:30 ingest capsules, after the effect protect metals await signal mask"). The grammar of the original is apparently unusual, as reflected in the translation.

The odd thing about the case is that nobody has the slightest idea what the two men were doing there, or what the masks were for. They were apparently both cut from sheets of lead into a shape resembling sunglasses (without the arms or earpieces at the side) and they might have been designed to protect the eyes, but it's not clear what they were protection from.

Some facts and other reports
Manoel Pereira da Cruz, 32, and Miguel José Viana, 34, were electronics repairmen. They lived in Campos dos Goytacazes, which is in the north of Rio de Janeiro state, 286 kilometres (178 miles) from the city of Rio. They reportedly left town on August 17, 1966, saying they were going to buy electronics supplies, and renting a car. They were last seen by a bartender when they stopped to purchase bottled water (the bottle was found near their bodies).

Theories
Charles Bowen of Flying Saucer Review reported in 1967 a number of interesting facts. A few months before, the two men had reportedly built a mysterious machine which had exploded. Four years earlier, another technician had been found up another hill with a similar mask. Bowen also collected testimony which Elcio Gomes, a friend of the two men had given to police, suggesting the men were "scientific spiritualists" who had built a machine attempting to communicate with Mars. Against claims that they were conducting an experiment or attempting some form of communication, no experimental apparatus was found with them on the hill.

A local "professor of yoga" reportedly told newspaper Folha de São Paulo that the local spiritualist community used psychedelic drugs as part of their rituals or communication practices. It has been hypothesised that the two men took an overdose and died. The identity or expertise of this yogi are unknown.

No evidence was found to indicate that the men had been poisoned, although there doesn't seem to have been much if anything in the way of tests done (the organs were reportedly not stored properly), so poisoning or a drug overdose may be possible. Other theories without any evidence suggest they may have been involved in a secret deal with nuclear material. Some sources suggest the masks were designed to protect against radiation poisioning. However this doesn't make a lot of sense as the masks would only cover their eyes, and a full-face mask (possibly with suit and hood) is more useful. Another even more ridiculous theory is that they were time travelers. There's no report that the men were examined for radioactive materials. Or for currency with dates in the future.

Brazilian newspapers reported that a round, orange UFO was seen on the hill on the night the men died. Sources say the area was considered a UFO hotspot. So the alternative explanation is that they were waiting for a ride with UFOs. It's not clear what killed the men, so presumably it was the aliens. The case seems to bear some resemblance to the Heaven's Gate suicides, where people killed themselves expecting to be carried away by aliens, although the evidence doesn't particularly support that. Nobody really has a clue, and it seems to have been a bizarrely incompetent police investigation. The most likely explanation appears to be that they went up the hill seeking to contact aliens and/or spirits, took some kind of drug, put on masks to protect themselves from bright lights or alien rays, and died, probably as a result of the drug, possibly accidentally, though due to the apparently sketchy investigation, especially the lack of toxicology tests, a more definitive answer seems impossible. The scant police evidence and rather vague and circumstantial stories documenting the events also seem responsible for creating the aura of mystery surrounding the case in a manner similar to how some apologists employ arguments from ignorance to posit miraculous explanations for poorly documented events in history, rather than the emotionally less satisfying answer, "We don't, and given the (lack of) evidence probably can't, know".