The Lead Masks Case and the Men Who Waited for a Signal
On August 20, 1966, a teenager flying a kite on a hill overlooking Niterói, Brazil, stumbled across a scene that seemed pulled from science fiction.
2 men lay dead beside one another in the grass.
Both wore suits beneath waterproof coats and crude lead masks over their eyes.
There were no obvious signs of violence, but police found a strange note with timed instructions to take capsules, protect metal, use the masks, and wait for a signal.
The men were electronics technicians who had reportedly experimented with unusual forms of communication.
Whatever they climbed Morro do Vintém expecting to encounter, they apparently came prepared.
More than 60 years later, exactly what happened on that hill remains unknown.
Two Technicians Take a Trip
The men were Manoel Pereira da Cruz and Miguel José Viana, from Campos dos Goytacazes in the Brazilian state of Rio de Janeiro.
On August 17, 1966, they left home saying they needed to purchase materials for their work.
Their journey eventually took them to Niterói, where they bought waterproof coats and a bottle of mineral water before heading toward Morro do Vintém.
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3 days later, Manoel and Miguel were found lying dead beside one another on the hill.
Investigators discovered their water bottle, towels, papers and other belongings nearby, while homemade lead masks covered their eyes.
They were crude sheets of lead shaped into oversized eye shields, yet somebody had deliberately made them and carried them up the hill.
Instructions From Nowhere
Among the men’s possessions was a handwritten note containing a bizarre series of instructions.
The original Portuguese lacked punctuation, making its precise meaning difficult to determine.
One commonly cited translation reads 
“16:30 be at specified place. 18:30 ingest capsules after the effect protect metals wait signal mask.”- Lead Masks Case records and contemporary reporting
The words sound less like a message than a checklist.
Were they supposed to swallow the capsules and wait for an effect before putting on the masks?
And what signal were these foos expecting?
If the notes were connected, the expedition appears to have been planned rather than improvised.
Nobody knew what the capsules contained.
What Were the Masks For?
Lead naturally raises the possibility of radiation because of its shielding properties, but protecting only the eyes while leaving the rest of the body exposed would be a strange defense against dangerous radiation.
Their backgrounds only deepened the mystery. 
Contemporary Brazilian reporting examined the men’s interest in unusual electronic experiments.
O Cruzeiro, one of Brazil’s largest magazines at the time, described clues involving
“experiences with strange objects in the middle of the night.”– O Cruzeiro
The magazine reported that theories surrounding the deaths ranged from espionage to flying saucers and extraterrestrial forces.
Accounts of the investigation also connected Manoel and Miguel with another electronics technician, Élcio Corrêa Gomes, who had reportedly participated in experiments with them.
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Later versions of the story increasingly associated these experiments with spiritualism and attempts to communicate with unknown intelligences.
Brazil already had a substantial spiritualist culture, making such experimentation less outlandish in its historical setting than it might initially sound.
Still, none of this establishes exactly what the men intended to accomplish.
The Autopsy Leads to a Dead End
If the mysterious capsules contained poison, drugs or some experimental substance, an autopsy should have provided the obvious answer.
Instead, decomposition complicated the investigation. 
The bodies had remained exposed long enough that forensic examination could not establish a definitive cause of death.
“The autopsy did not reveal elements capable of determining the cause of death, given the advanced state of decomposition.”- Official death record of Miguel José Viana, 1966
There were no injuries sufficient to explain why both men died, and toxicological evidence failed to provide a conclusive answer.
The one fact capable of pulling the story back down to Earth remained missing.
Whatever sealed their fate remains unknown.
Poison, Ritual or Contact Attempt?
The men may have swallowed a toxic substance during an experiment and died from poisoning.
If they believed the capsules would induce an altered state, they could simply have misjudged the substance or dosage, which might also explain the instruction to lie down.
The capsules, masks and electronic knowledge may have been components in an attempt to produce an altered state or communicate with something the men believed existed beyond ordinary perception. 
“What kind of death was on Morro do Vintém? From this planet, from other spaces, from another dimension?”- O Cruzeiro, Jorge Audi, 1968
Then there is the theory that turned the Lead Masks Case into an international mystery.
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Were they waiting for a UFO?
Reports of unusual lights eventually became attached to the story, and UFO writers interpreted the masks as protection against a flash or radiation associated with extraterrestrial contact.
Waiting for the Signal
Whatever the 2 electronics technicians expected to happen on that Brazilian hillside, they seem to have believed strongly enough in it to climb Morro do Vintém carrying equipment specifically prepared for the occasion.
Whether that signal ever came remains unknown.
By the time anyone found them, both men were dead.
References:
https://www.patreon.com/suenaga/posts/os-60-anos-do-de-100329025
https://pmig96.wordpress.com/o-enigma-das-mascaras-de-chumbo
https://pmig96.wordpress.com/o-misterio-das-mascaras-de-chumbo
https://pmig96.wordpress.com/o-misterio-das-mascaras-de-chumbo-2/