I think I know a little bit about this accident and the post above is pure conjecture along with a healthy dose of BS. Also, just for the record, Ernie Reichel, was the F/O, not the S/O on this flight.
Having flown Charlie Gilbert on at least 25 occasions on the DC6B, L188 and 707 I knew him best. Had flown with the two crew members several times each over a period of five years prior. This was a fatigue induced accident if there ever was one compounded by a number of irregular circumstances leading up to the departure. Reichel was going through a divorce so it's had to say where in mind was that night. No comments regarding the S/O.
One of the names mentioned early in this thread I believe was that of a Flight Attendant that survived the accident. If his stories regarding the Mexican authorities were to be beloved the US goverment should have banned any further bilateral aviation agreements between the two countries. Just say'n!