The U.S. Fish and Wildlife Service is investigating the death of Cecil, a lion in Zimbabwe that was hunted and killed this week by Minnesota dentist Walter Palmer, the agency announced on Twitter Thursday.



"We're investigating the killing of #CecilTheLion. Will go where facts lead. We ask Dr. Palmer or his rep to contact USFWS immediately," the agency tweeted, referring to reports that Palmer has been unreachable since publicly explaining how he came to kill the famous lion that lived on a preserve.

Two of the men Palmer paid $50,000 to help him hunt and kill the lion with a bow and arrow appeared in a Zimbabwean court on Wednesday to answer to charges related to their role of the protected animal's death, but local officials have not charged Palmer yet.

The incident has sparked outrage and inspired several petitions globally, including one through the White House's "We the People" platform. Since a New Jersey resident called on President Obama to revoke Palmer's passport, gun and hunting permits and dental license on Wednesday, 99,356 people have signed his petition. When it reaches 100,000, the White House is supposed to respond within 60 days, per its own rules for the site.

The petition also asked Obama to withhold federal payments to Palmer's dentist practice, which he closed after the controversy erupted.

Another petition asking the White House to extradite Palmer to Zimbabwe that began Tuesday has already hit more than 148,000 signatures.

The 13-year-old lion reportedly took 40 hours to die and was beheaded and skinned.

The incident has brought Africa's paid hunting industry into question just as Obama raised the issue of conservation and wildlife trafficking during his five-day trip to the continent.

Palmer's guides lured Cecil out of the nature preserve he called home, which could make his prosecution more difficult given that the animal did not die on protected land.