The antonyms for "un-investigated" are words that denote thorough scrutiny and examination. Some of the antonyms include thorough, extensive, complete, in-depth, comprehensive, detailed, exhaustive, meticulous, and rigorous. These antonyms reflect the opposite of "un-investigated" and imply that a proper investigation has been conducted. For instance, a thorough investigation implies that all aspects of the matter have been looked into and the findings are comprehensive, whereas un-investigated connotes a lack of inquiry or scrutiny. Therefore, if one wants to convey that a full investigation has occurred, they should use any of the above antonyms of "un-investigated.