Bloomington - The Minnesota dentist who killed Zimbabwean lion Cecil, sparking a global outcry from animal lovers, returned to work on Tuesday at his suburban Minneapolis office to shouts of "murderer" and "leave town" from a half dozen protesters.Walter Palmer, 55, did not speak to reporters as he entered his Bloomington, Minnesota, dental practice. He shut the practice in late July amid a firestorm of protests after he was publicly identified as the hunter who killed the rare black-maned lion weeks before.The River Bluff Dental practice reopened in mid-August without Palmer, who said on Sunday in a joint interview with the Minneapolis Star Tribune and the Associated Press that he needed to resume his duties.In the interview, Palmer reiterated a statement he had made in July: that the hunt was legal and no one in the hunting party realised the targeted trophy kill was the well-known 13-year-old lion. No charges have been filed against Palmer.Palmer said in the interview he wounded the lion with a bow and arrow, tracked it and then delivered a final blow with another arrow over the course of far less than the 40 hours that has been widely reported by media.The killing of Cecil triggered a storm of protests and threats on social media. Vandals spray-painted "lion killer" at Palmer's Florida vacation home and demonstrators built a small memorial of stuffed animals at the door of his practice and demanded he be charged and extradited.Veronique Lamb, a 49-year-old tourist from Brussels, was among the protesters waiting for Palmer on Tuesday. She said she was there to protest the dentist returning to work "like nothing happened.""He did something really bad and he really knows it," Lamb said. "Hopefully this has opened the eyes of people to this horrible business. It's very sad."Zimbabwe said in July it had requested Palmer's extradition as a "foreign poacher." Palmer would have to be charged in Zimbabwe before he could be extradited. The US Justice Department has said it does not comment on extradition requests.Regulated big-game hunting is permitted in Zimbabwe and a string of other African countries. Sceptical Cathy Pierce, 63, of East Bethel, Minnesota, said she would like to see Palmer lose his business. "Maybe that would send a message that this kind of hunting is not accepted anymore," Pierce said.Stephanie Michaelis, who lives across the street from the office, said she was sceptical of the protests. "What do we have to do with lions in Africa? They don't affect our lives," Michaelis said.Several messages were taped to the entry door to the building where the practice is located, including "From now on, donate your money to endangered animals instead. Apparently you have plenty" and "Justice for Cecil #extradition."A professional hunter in Zimbabwe was charged with breaching hunting rules in connection with the hunt in which Cecil was killed. He has denied any wrongdoing. A game park owner also was charged.Bloomington Police were at Palmer's office on Tuesday and have a security camera in the parking lot, Deputy Chief Mike Hartley said. The department has not received any reports of threats to Palmer's life, he said.