You're the second person that has mentioned the third group.
Sometimes the wolves dress up as sheep to sneak in for an easy kill.
Sheep, Wolves, and Sheep Dogs
http://mwkworks.com/onsheepwolvesandsheepdogs.html
Sheep,Wolves, Sheep Dogs......and Rams.
Sheep Dogs and Wolves are genetically the same animal, both predators.....the difference being that Sheep Dogs were systematically breed and trained to be beneficial......but the unique characteristics that make them useful to man is their predatory nature.
One can actually extend the analogy to good purpose by studying different types of predators.........Wolf like pack hunters, and lone stalkers, such as Leopards.......human predators respond in the same fashion.
Wolf like pack hunters would be gangs and groups of young men looking for prey.......they act very much like wolves and other pack hunters......they have a loose hierarchy, they stalk prey as a group. If you watch young men approaching potential prey you'll see them approach as a group, and often feel the prey out, to see what it does. As with wolves, running away is the CUE for the pack to ATTACK AND PURSUE!
Lone hunters use more stealth and guile......Ted Bundy was very skilled at approaching women to kill.......he would sometimes put his arm in a cast and have women help him to carry something to his car......then, when the moment was right......undetected movement for total surprise on the enemy/prey.......he would bludgeon them unconcious with his cast.
Lone predators are always tracking potential prey......their mouth may smile, but their eyes are always tracking......they attempt to deceive with words and actions.......a lone predator is one of the most dangerous animals a police officer or civilian will face.
Many police officers, like civilians, cue in to ego defense aggression as a threat......the guy venting, mouthing off, making threats......EVERYONE recognizes him as a threat, and he is......but the predator doesn't do that......he doesn't vent, he doesn't threaten......he's polite and cooperative......he waits patiently for the moment of COMPLETE advantage.....and when he ATTACKS it isn't like the wolf attack where they pursue and nip at your heels until they run you down.......it's an all out BLITZ to kill as QUICKLY AS POSSIBLE!
What is the best way to detect a lone skilled predator? The key is in arousal.....the skilled predator is calm.....calmer than he should be sometimes......let me use a police officer as an example.......being arrested is a traumatic experience for most people.....an emotional one. It is expected that most people will grumble and gripe, sometimes even argue. What should REALLY set off the bad radar, however, is the guy who DOESN'T argue, who DOESN'T gripe, who, say, is not only cooperative, but even OVERLY POLITE and cordial.......not in a nervous way, but in a smiling 'No problem, officer' way.......THAT guy is possibly dangerous! He may be controlling his arousal to paint you a FALSE picture.....put you off guard, make you slow to respond and distract you.......and moment he catches your GUARD down he'll KILL YOU!