A jury is a group of individuals sanctioned by the state to legally commit murder. If murder by individuals is immoral/illegal, then, by logic alone (unless you can prove those jury members possess some magical powers that an individual doesn't possess) murder by a group of individuals is also immoral/illegal regardless if it is sanctioned by the state or colluded to by a group of individuals.

Again, the original post was changing the semantics of an "evil" to fit political needs. Here, murder is being linguistically transmutted into "protection" or "justice" or "deterence" or any other number of rationalizations produced.