Why was Joseph Smith really killed?

Hello all. I’m a bit on the fence with my beliefs. Recently my brother in law posted an article in the fam chat talking about how unfortunate it is that Joseph Smiths death isn’t commemorated as a political assassination. I read through the article and then did some other research of why he died and am confused and hearing a couple different stories. One side says it was all political and another talks of his polygamy and him burning down a printing pres. I’m struggling now to understand what really happened. If you have any insight I’d love to hear it, please leave a link to any sources you have, I’d really appreciate it.