How does a spider bite lead to death in humans?

Jeff Hanneman is said to have died of liver failure due to a spider bite according to multiple web headlines. I’m wondering how the bite could have shut down the liver? Apparently there was dead tissue in Hannemans arm as well. But he opted not to get it amputated? How does the amputation not go through? Sorry I’m asking questions about someone’s death. But I’m extremely curious. I can’t find the type of spider that bit him either. At any rate rest in peace Hanneman.