Barack Obama is getting police officers killed. He is doing it recklessly and irresponsibly. No, he is not the one pulling the trigger. But as president of the United States - an office whose power and prestige he has never understood and certainly not respected the need to wield carefully - he is giving legitimacy to the narrative that police officers, not just a few individual bad apples but on a systemic basis, are out there looking to kill black people.
He is doing all this, by the way, as part of an ideological pursuit. Obama hates the idea of local police with local autonomy. He thinks all law enforcement should be under the direction of the U.S. Department of Justice - the same people who just let Hillary off the hook. And the tarring of local cops as racist monsters is part of how he hopes to build support for that idea.