Father Joseph Schweigl (1894—1964)
Father Schweigl conducted a detailed investigation on Fatima. In September 1952 Father Schweigl had met Sister Lucia.
Father Schweigl about the Third Secret of Fatima
In a letter to the Council Fathers of Vatican II, Father Schweigl writes that on March 27, 1952 he had received permission from Pope to speak with Sister Lucia «about 31 questions concerning the conversion of Russia». 
On September 2, 1952, authorized by the Holy Office, Father Schweigl did an interrogation of Lucia.
Although the Holy Office did not authorize the publication of this interrogation, on his return to the Russicum Father Schweigl confided this to one of his colleagues who questioned him on the Secret:
“I cannot reveal anything of what I learned at Fatima concerning the third Secret, but I can say that it has two parts: one concerns the Pope. The other, logically — although I must say nothing — would have to be the continuation of the words: In Portugal the dogma of the Faith will always be preserved.”
… Father Schweigl himself recalls in 1963, in his text reserved for the Council Fathers, that «in 1952, the Archbishop of Coimbra demanded that the replies given by Sister Lucy not be published without authorization of the Holy Office; up to the present this authorization has not been given.»