They opposed the rise of the executive power which they viewed as illegitimate
It was predicted that James Earl Ray killed Martin Luther King Jr. due to his persuading speech. He was worried that if his speech touched many people's hearts and persuaded them against slavery, then slavery would end, but he WANTED to keep having slavery! So, before Martin's speech got slavery to end, he had to end Martin's mouth by taking away his life.
I hope this helps! :-)
