Shredder and Krang
 

Shredder repeatedly tried to kill April, Splinter and the turtles. Splinter and the turtles aren't people. April is a person. That's attempted murder.

Krang almost killed Baxter Stockman too but not illegal in Dimension-X.

Uh, yeah? I don't think the trained assassin and warlord are characters who really care about human life, if either of them murdered anyone, it would only be weird because it would have happened in a children's show that already removed murder from the origin story.