RIVERTON — In his document detailing the legal conclusion to an investigation into the Sept. 21 officer-involved shooting in front of Walmart in Riverton, Fremont County Attorney Patrick LeBrun cautioned the public against further proceedings in the matter.

The shooting killed 58-year-old Anderson Antelope Sr.

LeBrun wrote that because the Riverton Police Department officer who shot Antelope did so because Antelope placed the officer and several bystanders in “immediate peril” by swinging a six-inch knife.

The officer had the right to “take all actions necessary at that moment to...