Alma 47 tells the story of a wicked and cunning man named Amalickiah who plots (successfully) to eventually become king of the Lamanites. The first part of his plot is to gain control of the Lamanite army. Having a smaller army already under his control, Amalickiah agrees to turn over his army to Lehonti, the Lamanite general, as long as Lehonti agrees to make Amalickiah the second in command of the entire army. The next step of this wicked man is obvious:
"Amalickiah caused that one of his servants should administer poison by degrees to Lehonti, that he died. Now, when Lehonti was dead, the Lamanites appointed Amalickiah to be their leader and their chief commander." (Alma 47:18-19)
It is not mentioned what type of poison was used for this murder, but clearly the people involved knew what they were doing as they administered the poison very carefully, little by little, until it had its desired effect.