That sort of thing is far less common, and far less dangerous, than the problem of damning bits and pieces coming out before the full picture is revealed, and obscuring the actual facts of the matter. The most famous example of this is the execution of Nguyen Van Lem* during the Vietnam war, but it is far from the only such case. There are many cases, for example, where protests, street violence, and even riots have broken out over "police brutality" when in fact the officer in question was nearly killed before using force (commonly, these involve very large suspects and fairly small cops. The specific example I'm thinking of was a female officer (white) that repeatedly tased a (black) suspect that was already handcuffed. In this case, swift release of the hospital report and dashcam video showing said suspect (who massed at least double, maybe even triple what the officer did) hurling her several feet through the air repeatedly, coupled with lots of kicking, despite being restrained by handcuffs.) Other common situations involve fatal shootings where the initial report is spread far and wide, but the fact that it is confirmed that they were legitimate defensive attacks (such as an incident where a woman shot and killed an intruder that followed her and her small children into the attic with a crowbar) never reaches anywhere near the wide spread of information.
*For the uninitiated, Lem was identified by South Vietnamese intelligence as leading a "death squad" that specialized in terror massacres, and was captured in civilian clothing right next to a mass grave containing dozens or hundreds of victims of such a "death squad," among which bodies were the executing officer's closest friend and his entire family. The photographer that took the famous shot has since declined all awards and royalties from the photo, and has stated that he wished he had never published it.