Like myself, you have no idea of what actually caused his death. Well unless you personally conducted his post mortem examination.
The taser might have caused his death, the taser might not have caused his death. Nobody knows at this stage.
Likewise none of us know enough about what actually went on to say whether the use of taser was justified or not.
Well that's bollocks. Cardiac arrest caused his death. I do know that the police are often over zealous in using force. I do know that there are clear associated risks associated with the use of tasers. As such they should only ever be used as a last resort in my opinion. I know that this is often not the case.