The Bureau of Indian Affairs has taken over the investigation into Olivia Lone Bear's disappearance.
Nedra Darling, public affairs director for the BIA's Department of the Interior, said the BIA will take the lead on the investigation for the missing New Town woman.
"The tribe and family has asked the BIA Office of Justice Services to take over this missing person investigation," Darling said Friday. "BIA has taken the lead in the investigation and is following up on all tips and leads."
Matthew Lone Bear, who has led volunteer efforts to find his sister, said the move is "definitely a step in the right direction."
In December, the Tribal Business Council of the Three Affiliated Tribes passed a resolution authorizing lead investigative responsibility to the BIA. Tribal directors, police and the Lone Bear family met Thursday to discuss the BIA's role.
MHA Chairman Mark Fox, who could not attend the meeting as he was in Bismarck, said the BIA's involvement and resources until now "have been helpful but limited."
"But with all efforts so far, the goal is to improve our search operations with the ultimate hope of locating one of our missing tribal members," he said.
While Matthew Lone Bear said tribal police will continue to assist the search, tribal police did not return phone calls and messages left Thursday and Friday regarding its role.
Three Affiliated Tribes Police Detective Sam Lincoln previously said police continue to conduct interviews and search for the missing 32-year-old mother of five.
Volunteer searchers are requested to scour various North Dakota cities for the truck connected to Olivia Lone Bear's disappearance. She was last seen driving a teal 2011 Chevrolet Silverado 2500, with North Dakota license plate 839 BRC.
Interested volunteers may call Matthew Lone Bear at 701-595-3114.