CHEYENNE, Wyo. (AP) — Investigators looking into the fatal crash of a search and rescue helicopter in Wyoming say wintry weather may hinder plans to remove the chopper from the backcountry on Friday.

Michael Huhn of the National Transportation Safety Board says the probe into Wednesday's crash in northwest Wyoming is in the early stages.

He says it will take nine months to a year to determine an official cause of the crash.

Huhn says the helicopter's pilot told him that the aircraft began to spin and descend while hovering about 100 to 200 feet above the trees.

Longtime search and rescue volunteer Ray Shriver, of Jackson, was killed in the crash. The rescue team was responding to help Steven Anderson, of Morris, Minn., who died of injuries in a separate snowmobile accident.