The killing of 35-year-old Native American man Paul Castaway by police in the US city of Denver has sparked outrage and protests. 

Castaway's mother, Lynn Eagle Feather, says she called the police for help on Sunday after her son threatened her with a knife, telling cops he was mentally ill. Police allege Castaway charged at them with the knife, but according to witnesses and a surveillance video seen by a local reporter, Castaway was holding the knife to his own neck when he was shot four times.

Speaking to Indian Country Today, Eagle Feather said the police shooting was racially motivated. 

"I want justice for my son. I want those cops to be reprimanded. These Denver cops love to kill Natives. They love to kill people of color here,” she told the network.

The killing was met with outrage online.