Two of the accused, Raphael Joseph and Warren Ballentine, explained that they had only planned on committing a robbery, and that things got out of hand because one of the co-defendants, Ishmael LaBeet, was adamant that they also make "a political statement" because "he was angry about foreigners coming in to take our money and leaving us with nothing." According to Joseph, LaBeet, during the commission of the robbery, suddenly began shooting people.
This all conveniently was not brought up because
it's just a portrayal of a setup.