If I may postulate something a little different.
All homo sapiens are included in the animal kingdom. Therefore all homo sapiens are animals. Some homo sapiens transcend that and become human. In my opinion being human means knowing the difference between right and wrong, having a conscience and having compassion for others.
This is not to mean that those who have not become human are less intelligent.
Drawing a line and saying one side is human and the other is animal is nearly impossible. Hindsight sometimes is easier, psychopaths are obvious, those who feel that the rules/laws are for others and not them.
It is my contention that some are not human and when so identified should be treated as an animal.
Note; I am drawing a difference between homo sapiens and human in order to make the argument
I cannot agree with you here.
Even the worst and most evil humans are still humans and need to be treated as such. A man-eating bear needs to be shot or relocated to an area where it won't have contact with humans. Human beings, unlike animals, are capable of knowing better and should be held to higher standards than animals which are simply acting in accord with their instincts.
Charles Manson, Stalin, Hitler, Pol Pot, and other horrible people are still created in the image of God. As such, they deserve fair trials of the facts in civilian cases, or to be treated according to the laws of war which in the West are based on Judeo-Christian principles.
A human is not an animal. Inhumane treatment for humans who act like animals doesn't show respect for truth; it simply debases the judges, police, and society as a whole down to the level of animals.
Bottom line: Yes, punish evildoers, but remember that an evil human is still a human and deserves punishment for not acting like a human should act.