WASHINGTON, July 30 (UPI) -- U.S. Fish and Wildlife officials said Thursday they wish to talk to the Minnesota dentist who admitted killing Cecil the lion -- prompting worldwide uproar -- but have been unable to find him.
Walter Palmer, a dentist in Bloomington, Minn., issued a statement earlier in the week expressing regret for killing the 13-year-old lion during a hunt earlier in July. He also offered to assist authorities in the United States and Zimbabwe in their investigation of the kill, which Zimbabwe wildlife officials say was illegal.
But so far, U.S. officials have had no luck tracking down Palmer.
Dan Ashe, the director of the U.S. Fish and Wildlife Service, went on Twitter on Thursday, calling for Palmer to contact the department.
"#CecilTheLion #CNN reporting Dr. Palmer seeking to cooperate. EZ to do. U or ur representative please contact #USFWS immediately," he wrote.
The FWS Twitter account also called for Palmer's cooperation.
"We share your concern about the issue surrounding #CecilTheLion and we're working to gather the facts," a tweet said.
Edward Grace, the deputy chief of law enforcement at the agency, told The Hill that so far, "multiple efforts to contact Dr. Palmer have been unsuccessful."
Investigators have attempted to make contact with Palmer at his home and his dental office, and through multiple phone numbers and his email, The Washington Post reported.
Palmer said he paid professional guides for a private safari to stalk the 13-year-old lion and kill him. The Zimbabwe Parks and Wildlife Management Authority said the group of hunters allegedly lured Cecil out of the protected Hwange National Park using bait.
"To my knowledge, everything about this trip was legal and properly handled and conducted," Palmer said in his statement.
Cecil was shot with an arrow and stalked for 40 hours before he was shot with a gun. The lion's decapitated and skinned body was found by wildlife officials using a GPS tracker.
It's unclear if Palmer will face any charges for Cecil's death either in the United States or Zimbabwe.
The incident has prompted backlash against the dentist both in his hometown -- people have left scathing notes and a memorial to Cecil at his office doors -- and on social media.