Complex sentence: One was published in 1918 in "The Sphere" newspaper, which was before the originals had been seen by anyone outside of the girls' immediate family, leading to the hypothesis that the adults could have been part of the conspiracy.
Split into simpler sentences: One was published in 1918 in "The Sphere" newspaper, which was before the originals had been seen by anyone outside of the girls' immediate family. The article therefore hypothesized that the adults could have been part of the conspiracy.