Cecil the lion killer Walter Palmer has been warned "the world will hunt you down" in a message left outside his holiday home.
A sign, with a lion cuddly toy attached, was taped to the front door of the property in California.
It reads: "You are an abomination - the world will hunt you down. Cecil Innocence."
Palmer has not been seen since news of the lion's death broke sparking a furious backlash from animal rights campaigners around the world.
American philanthropists have pledged to match new donations up to $100,000 to the research team who had been tracking Cecil since 2008.
Dozens of protesters gathered outside the practice of a suburban Minneapolis dentist who killed a protected lion in Zimbabwe.
A host of celebrities have taken to social media to speak out on the killing of well-known lion Cecil in Zimbabwe by a US dentist.