Complex sentence: After eliminating them, he located one of the six Infinity Gems; some time before, the six Illuminati located the Gems and each member took possession of one, to make sure they would never again fell into the wrong hands.
Split into simpler sentences: After eliminating them, he located one of the six Infinity Gems. Some time before, the six Illuminati located the Gems and each member took possession of one to make sure they would never again fell into the wrong hands.