An American dentist who admitted that he killed a well-known lion this month in Zimbabwe and planned to mount the head kept his office closed on Wednesday as the furor about the hunt turned vitriolic and, at times, threatening.

A memorial to Cecil the lion outside Dr. Walter J. Palmer's closed dental office in Bloomington, Minn.

Cecil had been closely studied by researchers at the University of Oxford since 2008 as part of efforts to study a decline in Africa’s lion population and to better understand the threats the animals face.

According to the Zimbabwe Conservation Task Force, the lion was shot with a crossbow after he was lured out of the sanctuary, following the scent of food.

The hunters tracked him for about two days before he was killed with a gun, conservation officials said. He was beheaded and skinned, his corpse left to rot.

Activists used search engines to find Dr. Palmer’s contact information and social media to share information about his business and his family, stirring a fever pitch of anger strong enough to effectively dismantle his digital life.

The 13-year-old lion, recognizable by the black streaks in his mane, suffered a slow death, according to the Zimbabwe Conservation Task Force.

The hunter tried to destroy the GPS collar that Cecil was wearing as part of research backed by Oxford University, the group said.

Thousands of people have read the story and have also been shocked. Their eyes opened to the dark side of human nature. Surely they will now be more prepared to fight for the protection of wild animals and the wild places where they live. Therein lies the hope.