The actions of the dentist were abhorrent, and I truly believe that he knew that what he was doing was illegal, and that he is only sorry that he was caught as opposed to being truly remorseful over his actions. For the record, I agree that a lot of people are outraged over this story simply because lions are thought of as noble, majestic and generally attractive creatures in our collective consciousness. However, there are legitimate reasons to be angered by this story too:
1) Cecil was baited out of a protected wildlife park using a carcass which was tied to the back of the vehicle that the dentist was travelling in, and was subsequently shot once he left the boundaries of said park. The dentist knew that this animal was meant to be protected, but decided to hunt it anyways.
2) Cecil was wearing a tracking collar as a part of a research project being conducted at Oxford University. These collars are not subtle. In fact, they are pretty hard to miss. Seeing the collar alone should have alerted the dentist that hunting this lion would be a big mistake.
3) The dentist and his hunting party attempted to destroy the collar after the hunt, presumably to get rid of any evidence. This is a serious crime in and of itself, even ignoring the other illegal acts which transpired.
4) This dentist, who claims to be remorseful over his actions, reportedly had plans to hunt an elephant immediately after killing Cecil, but turned the opportunity down when the guides couldn't find him a target with what he deemed to be a suitable amount of ivory.
5) Lions aren't like black bears, a species that actually requires sustainable hunting practices in order to keep their population numbers from exploding. In the past 70 years, lion population numbers have dwindled from an estimated 450,000 to just 23,000. When a species is approaching near-endangered status the way lions are, there is no such thing as sustainable hunting practices with regards to them. Every individual loss is detrimental.
This dentist is nothing more than your average garden variety poacher. He should be extradited to Zimbabwe to stand trial and answer for his crimes. That being said, posting the dentist's personal information on social media and making threats of violence against him as some have done is absolutely wrong and not the way to go. This should he handled by the proper authorities, and not via vigilante justice.