Palmer sent an email to patients insisting he did not know Cecil was a protected lion. This comes as the guide who led that hunting trip in Zimbabwe suggests Cecil was not the only animal Palmer wanted to kill, CBS News' David Begnaud reports.
In an exclusive interview with British newspaper The Telegraph, Palmer's guide, Theo Bronkhorst, said the hunt went "wrong from the beginning."
"We were never meant to hunt on the land where this lion was shot," Bronkhorst said.
Bronkhorst said an elephant carcass was "dragged and moved into the long grass and used for bait."
He claims Palmer shot an arrow at Cecil but wasn't sure if the beloved lion was hit. The next morning, the injured animal was found, and Bronkhorst said Palmer finished him off with a second arrow.
Later, Bronkhorst said Palmer asked "If we would find him an elephant larger than 63 pounds ... (the weight of one tusk), which is a very large elephant, but I told him I would not be able to find one so big, so the client left the next day."
Authorities in Zimbabwe said they will hold Palmer "accountable" by seeking his extradition.
"This is the route that we are taking as Zimbabwe," Zimbabwean Minister of Environment, Water and Climate Oppah Muchinguri said. "We are taking the issues very seriously."
The U.S. signed a treaty with Zimbabwe in 1997 which allows someone charged with or convinced of a crime punishable in both countries to be extradited.
The U.S. Fish and Wildlife Service said a representative of Palmer has contacted the agency and that "an investigation is ongoing."
The 55-year-old avid hunter has been vilified all week. Demonstrators protested outside his dental office in Bloomington, Minnesota.
Palmer told patients in an email he would resume normal operation as soon as possible. Meanwhile, some of his personal information has been shared on social media, which has turned into a public shaming.
Nick Pinizzotto, CEO of the Sportsmen's Alliance, a pro-hunting group, is troubled by the backlash.
"You see many people putting the lives of human beings behind the lives of animals, and that's a scary proposition for anybody," Pinizzotto said.
International Fund for Animal Welfare Regional Director Jeffrey Flocken said this hunt highlights a global problem.
"While Cecil was iconic and people were very invested in this particular individual, hundreds of lions are killed every year for sport," Flocken said. "So, while this is an incredibly sad situation, it's forcing us to look at what we do right now with other imperiled animals. Not only are lions killed for sport, but so are elephants and rhinos, species that we know are declining, like giraffes and leopards. Why do we allow this to happen?"
As of Saturday morning, almost 200,000 people have petitioned the White House to extradite Palmer to face justice in Zimbabwe. Since the U.S. signed the extradition treaty 15 years ago, no one has been extradited there to face criminal charges.