The papers include correspondence, photographs, diaries, journals, publications and vital and legal documents, such as his birth certificate, passport and insurance papers documenting Armstrong's days at Amherst College and Harvard University, his foreign language studies and a 1959 automobile trip to Africa.

Also contained in the papers of John Armstrong are those of his mother, Catherine M. Armstrong. They relate almost exclusively to her son's death and include correspondence with the families of Armstrong's fellow travelers, official correspondence relating to the investigation, notes on her trip to Paris to visit the family of Tommy-Martin and notes of sympathy following her son's death.

Note that correspondence from JHA to his mother is filed with JHA's correspondence. Letters to Catherine Armstrong relating to JHA's legal bank accounts and insurance policies are filed with JHA's vital and legal records.