RATON, N.M. — A husband and wife who pushed for political change in Zimbabwe, an adventurous Texas investor and a pair of decorated pilots died in a fiery helicopter crash in a remote area of New Mexico. Investigators will comb through the charred wreckage in search for clues as to why the helicopter carrying the group of prominent friends went down after dark Wednesday. Friends and family members confirmed Thursday that Zimbabwe opposition leader Roy Bennett and his wife, Heather, had traveled to New Mexico to spend their holiday with friend and wealthy businessman Charles Burnett III at his ranch.