[user104658]

To be fair... To say that a taser is not a potentially deadly weapon is just not true. They can do a lot of damage in the wrong hands up to and including killing someone. They couldn't reasonably just let someone go home with a deadly weapon stolen from the police and pick it up later... That would be insanely reckless.

However, they knew for a fact that he only had a taser, so why did they not use... Tasers? Why use a firearm that's far more likely to cause a fatal injury?

Again it's one of those situations where I can't help but think, if it had happened in the UK this person would be alive because shooting him wouldn't have been an option. They would have found another way to apprehend him and get the weapon back. Which means, its obviously possible to police without relying on lethal force... And it feels like in places where they have the option, it's often used out of simple habit, laziness or fear.