HELENA, Mont. (AP) — The Lewis and Clark County sheriff, three deputies, search and rescue members and others are heading into the Bob Marshall Wilderness to try to solve a nearly two-year-old mystery.

What happened to Noah Pippin?

A backcountry ranger, a group of hunters and a Great Falls family all reported seeing Pippin on Sept. 15, 2010 along the Chinese Wall. The Michigan native has not been seen since.

His family has continued to try to find out what happened to the 30-year-old Marine who was a veteran of three tours of duty in Iraq.

Sheriff Leo Dutton has recruited a behavioral specialist and an outdoorsman to give him advice as to where to look for Pippin.

The weeklong search was to begin Wednesday.