As for the bolt-gun killer, there must be more to it than that. The guy in the video was white and had the tattoo.
When Detective Bowden's first episode aired, my immediate thought was that a shapeshifter or chameleon type of troubled person killed him and took his place, and was actually burying the real Bowden at the end of the episode. But who knows with this show? The bolt gun killer could go around possessing bodies for all I know.