Sixteen protesters who were part of the six-week armed occupation of the Malheur National Wildlife Refuge in Oregon pleaded not guilty Wednesday to charges of conspiring to impede federal officers. Ten of the 25 people indicted in the incident appeared in court in Portland, while six others waived their right to attend the arraignment. The arraignment came a day after the FBI announced it had finished examining the refuge for evidence. Federal prosecutors said they expect a grand jury to return two superseding indictments that could bring new “charges and defendants,” according to court documents. A status hearing was set for March 9.