Big Game Hunter's Killing of Well-Known Lion Engenders Anger

The well-publicized case of a Minnesota dentist and big game hunter who shot a killed a well-known and well-loved lion named Cecil  during a hunt in Zimbabwe recently, has brought howls of anger from all over social media. People have posted negative reviews on the Yelp page of his dental practice, there has been a makeshift memorial for the lion at the office of the practice (which is temporarily closed due to the heavy traffic of phone calls and visitors), and national and international news organizations and celebrities have condemned the practice.

The reasons for the anger are many: With dark fur along his back, Cecil was an easily recognized and well-known part of the nature preserve where he lived, he was lured out of the preserve (illegally) by the people hired by the Dr. Palmer, and after he was shot by Palmer, he lived for more than a day in pain, until he was tracked and dispatched with a bullet.  After he was dead, he was skinned, beheaded and his carcass was left where he died.

What can we look at through the lens of ethics in this case?
-Is big game hunting ethical?
-Are there ethics associated with hunting that Dr Palmer transgressed?

Firstly, big game hunting can be done ethically, according to multiple sources on the web, as long as certain rules are followed, such as "Obey all laws", "Fully use the animal" and "Use an appropriate weapon", among others:
http://thebiggamehuntingblog.com/2015/02/6-hunting-ethics-that-every-new-hunter-should-know/

These rules ensure that the animal is not needlessly suffering when it is killed and that its death will be beneficial to the hunter and the hunter's family in an elemental way-through eating and use of the carcass. The rules outlined in the above site are echoed all over the web, and they seem contrary to the style of hunting of Dr Palmer; his hunting party flouted local laws when it lured Cecil out of the nature preserve, they did not use all of the carcass, and one of the rules, "Use a powerful enough weapon", is for the specific purpose of cleanly and quickly killing the game so that it won't live in agony like Cecil did due to being shot with an arrow.  According to these rules Dr. Palmer was not ethical in his hunting of the lion.

The investigation will continue, and we will see how Dr. Palmer is punished (or even if he is).  Until then, he is very much being punished in the court of public opinion - it is very likely that he has lost a good bit of business and he is (for the time being) infamous as being "the hunter who killed that beloved lion, Cecil".  I have no doubt that he will be receiving death threats and his family will be dragged out into the limelight to suffer as well.  Hopefully, when this story is replaced with some other story, and the investigation is complete, he will be punished if appropriate, according to laws he broke and he will not be buried under an avalanche of vengeance.

http://www.seattletimes.com/nation-world/international-outcry-over-death-of-lion-brands-big-game-hunter-as-villain/