MINNEAPOLIS (REUTERS) - Police in Minnesota are investigating reports of a threat against a dentist who killed Zimbabwe's most famous lion just outside a national wildlife preserve, sparking a global firestorm of hate messages on social media.
Demonstrators were gathering on Wednesday afternoon outside the suburban Minneapolis office of Walter Palmer, 55, an avid big game hunter, who said in a statement he regrets killing the huge cat known as Cecil on July 1.
He said he had hired professional local guides who secured hunting permits and believed the hunt was legal.
As of Tuesday, Palmer had temporarily closed his office, River Bluff Dental, in Bloomington, Minnesota, amid wishes for his death and widespread criticism of his hunting on social media and under business reviews on Google and Yelp.
Cecil, a distinctive black-maned lion, was lured out of Hwange National Park using a bait and was wounded with a bow and arrow, and not shot dead until 40 hours later.
Bloomington Police have stepped up patrols around the office and are investigating a phoned-in threat, Deputy Chief Mike Hartley said.
"A terroristic threats report related to this incident was taken by our police department yesterday and will be investigated like any other similar offense report," Hartley said in an e-mail.
The Minneapolis-based Animal Rights Coalition said a protest was planned on Wednesday at the office, where a small memorial of stuffed animals was placed at the building entrance.
Palmer, who has not been charged, has been under official scrutiny for his hunting in the past. He pleaded guilty in 2008 to lying to a US Fish & Wildlife agent about a black bear hunt in Wisconsin two years earlier.
He had faced federal charges of killing a bear outside his permitted zone and then hauling it back 64km inside to register it with authorities.
US Representative Betty McCollum, a Minnesota Democrat, has asked prosecutors and the US Fish and Wildlife Service to investigate whether any US laws were violated in the lion's killing.
"We are currently gathering facts about the issue and will assist Zimbabwe officials in whatever manner requested," said Vanessa Kauffman, a spokeswoman for Fish and Wildlife.
"It is up to all of us - not just the people of Africa - to ensure that healthy, wild populations of animals continue to roam the savanna for generations to come."
Palmer said in his statement he had not been contacted by authorities in Zimbabwe or the United States and would assist in any inquiries.
A spokesman for the US Attorney's Office in Minnesota declined to comment.
The attorney who represented Palmer in his Wisconsin case could not be reached immediately for comment.
A professional hunter, Theo Bronkhorst, pleaded not guilty in a Zimbabwean court on Wednesday to a charge of "failing to supervise, control and take reasonable steps to prevent an unlawful hunt" when Palmer killed the lion known as Cecil.
If found guilty, Bronkhorst could be fined US$20,000 (S$27,000) and possibly jailed for up to 10 years.
The Pope & Young Club, a Minnesota-based bowhunting and conservation organisation that includes Palmer among its members, said on Wednesday it was looking into the hunt, though it focuses only on North American big game.
The club said its ethical code calls for fair chase of animals, which does not allow the hunter an unfair advantage, and does not condone violations of that code.
Change.org had at least half a dozen petitions on Wednesday ranging from calls for Palmer's extradition to appeals for US President Barack Obama to help create laws to protect big game animals and Minnesota to revoke Palmer's dentistry licence.
Even US comedian Jimmy Kimmel weighed in on the lion hunt.
"I am honestly curious to know why a human being would feel compelled to do that - how is that fun?" Kimmel said on Tuesday night on his network television show.
"Is it that difficult for you to get an erection that you need to kill things?"