The phrase "were in possession of" can be replaced with several synonyms to add variety and clarity to writing. Some alternatives include "had," "owned," "held," "controlled," "commanded," "gained," "acquired," "secured," "obtained," "took," and "possessed." Using these synonyms can make a text more engaging and impactful. For example, "The suspects were in possession of illegal weapons" can be rephrased as "The suspects had unlawful arms," "The suspects possessed illicit firearms," or "The suspects acquired prohibited weaponry." Replacing the phrase with any of these alternatives can make the sentence easier to read and understand while still communicating the same message.