Dear Wandra,
There is a book called “Heroes and Heroines of the Ten Year Crusade in Southern Africa” (by Lowell Johnson e Edith Johnson), that mentions many of the early Baha’is in Angola and Mozambique. This book has short biographies of those Baha’is from Malanje and Luanda in the 1950s and 1960s. Several were arrested by PIDE and sent to the prison camp at Baia dos Tigres.
The interesting point for me was to find copies of PIDE’s archives (at the Baha’i Center in Lisbon) with statements and documents from Mr. Sampaio and other Baha’is.
Unfortunately, I have not found any official document mentioning Mr. Sampaio’s death. I presume his death wasn’t registered, like many other Angolans who died at the hands of PIDE in those days.