Cecil was one of Africa's most beloved lions, but he was killed during a trophy hunting expedition earlier this month.
Authorities say Walter Palmer, a Minnesota Dentist, killed the animal after his guides lured the lion out of the park by tying a dead deer to their car. The hunters, who are now facing charges, shined a spotlight on Cecil while Palmer shot him with an arrow.
40 hours later, they say the men tracked the wounded animal, killing it with a gun. It was only then, the hunters say they realized Cecil was part of a study when they discovered his GPS collar and tried to destroy it.
"There is no justification in killing an animal that wasn't bothering anybody else," said Christopher Flugge.
Flugge is one of many protesters who have left stuffed lions in front of Palmer's Minnesota dental office and scathing reviews on social media. Palmer, who reportedly paid $50,000 for the hunting expedition, has gone into hiding.
On Tuesday, he issued a statement which read in part, "I relied on the expertise of my local professional guides to ensure a legal hunt. I deeply regret that my pursuit of an activity I love and practice responsibly and legally resulted in the taking of this lion."
Legal or not, opponents of so called "trophy hunting" are using the incident to renew calls to ban the practice across the globe.
"Killing such an animal just because you want to have a picture and maybe the skin on your wall, for me it is a form of sickness," said Ioana Dungler, the Director of Lionsrock, a sanctuary for big cats in South Africa.
Jimmy Kimmel spoke about Palmer and Cecil's death during his monologue Tuesday night.
"I'm not against hunting. If you're hunting to eat or to keep the animal population healthy or if it's part of your culture or something, that's one thing. But if you're some a-hole dentist who wants a lion's head over his fireplace in his man cave so his buddies can gather around it and drink scotch and tell him how awesome he is that's just vomitous," said Kimmel.
The late-night host even became choked up as he called on his viewers to donate to the wildlife conservation research unit at Oxford, the group that had been studying Cecil.
"If you want to make this into a positive. You can... uh... sorry... okay I'm good. Make a donation to support them. Maybe we can show the world that not all Americans are like this jackhole here, this dentist, this top dentist."
This isn't the first time Palmer has been surrounded by controversy for trophy hunting. In 2008 he pleaded guilty to lying to U.S. wildlife officials about where he shot a black bear in Wisconsin. But even if Palmer does come out of hiding and answer questions for authorities, it's unlikely he'll face any charges for his actions in the killing.