joining us, a Minnesota dentist is being bombard tonight with threats, petitions, even boycotts, all because he killed a beloved lion in Africa for sport. He claims his killing of Cecil the lion was... See More
joining us, a Minnesota dentist is being bombard tonight with threats, petitions, even boycotts, all because he killed a beloved lion in Africa for sport. He claims his killing of Cecil the lion was legal, but it's reigniting a fierce debate about big game hunting. Here's David Wright. Reporter: In Zimbabwe, Cecil was as famous as simba, that is until this Minnesota dentist came along like some modern-day Ernest Hemingway. Dr. Walter palmer paid $55,000 for a license to hunt in Zimbabwe, hiring local guides to help him. Authorities say palmer and his guides illegally lured Cecil out of the national park where he was protected, by tying a dead animal to the fender of their car. Once outside, palmer allegedly shot Cecil with his bow and arrow, injuring him. Then authorities say a gps tracking collar on the lion shows how they proceeded to stalk him for more than a day, finally killing Cecil, who was beheaded and skinned for a trophy. It upsets me that people can be so stupid to take a life like that is correct whether it's human or not. Reporter: Now the hunter is being hunted himself. The dentist seen here in a promotional video for his practice, quickly becoming one of the most hated men on the internet thanks to websites like buzz feed. Today his dental clinic locked tight, protesters leaving little stuffed animals outside. His Facebook page suspended because of the angry roar. You kill defenseless animals, we kill your business, wrote Emily P from New York. Charlie wrote shame on you, killing a majestic creature. Lions should not be killed for sport! On Twitter one person summed it up this way. Think it's safe to say that the dentist is the most hated man in the world right now. Good stuff. Today Dr. Palmer released a statement, insisting I had no idea the lion I took was a known local favorite, adding that he relied on the expertise of my local professional guides to ensure a legal hunt. I deeply regret that the pursuit of an activity I love and practice responsibly and legally resulted in the taking of this lion. He said he has not heard from authorities in Zimbabwe or the U.S. He has a conviction in this country for poaching a black bear. Lying to federal game wardens on two occasions about where he killed it. A crime that could have carried a five-year sentence. He pled guilty and got one year probation. Any hunter actually worth a damn will find it incredibly disrespectful. Reporter: It seems those manly old photos of Roosevelt and Hemingway, big game hunters out on safari don't translate so well in the era of instagram and Facebook. Not brought up to relate to simba of lion king, a generation brought up to revere island. And from the chronicles of narn yeah. Killing an animal for sport? Not unless you're a white witch. The laien he kills what incredibly popular, a male with cubs. Coming right up to the tourists. He was one of the most magnificent lions I've seen. I've seen a lot in captivity and different areas but this one was very special. And that's why people remember him, because he was such a special anma'am. Reporter: And that only feeds the outrage factor. Palmer is not the first big game hunter to come under fire. Melissa balkman's smiling picture with a dead lion led to a national outcry. There was a petition to ban her from returning to South Africa. Her reality show capitalized on it. Check out the size of this wra rack. Reporter: Many say hunting should be for eating. Not trophies. Like palmer, she's a bow hunter. She got a taste of online rage herself after posing with a 510-pound bear she'd just killed in North Carolina. Threats poured in on Facebook. She says she had 5,000 death threats in one day. They don't understand that we eat all that meat. What are they eating at their dinner table? Do they have meat on their plate? Do they go to whole foods and buy a $20 steak? Reporter: In the case of the dentist, Walter palmer didn't eat any Cecil the lion steaks. He didn't get to keep the head or the pelt. He and his guides had to leave their trophies behind in the bush once authorities started coming after them. Mayan the conservationists have dedicated their lives to studying these animals. Species like this, we have to contain those that we have. And, you know, going out to shoot deer in New Jersey, that's a completely the different conversation, shooting the last of the lions is dramatic. Reporter: Not only did palmer kill Cecil the lion, he essentially killed all of his cubs. Any new male taking over the pride will likely kill them off to make way for his own cubs. His two african guides now face poaching charges in Zimbabwe. The dentist may face charges too. He's already back in the states. Instead, justice for Cecil is shaping up to be this very public shaming of the dentist. I'm David Wright for "Nightline" in New York.
This transcript has been automatically generated and may not be 100% accurate.