I don't have a theory. My guess is that he probably died when his jet was shot down. Most of the suggestions to the contrary which I'm aware of are based on pretty sketchy, circumstantial interpretations of "clues." I'm calling Occam's razor on this one - just an opinion.
Brett
"During the December 1995 survey, the Iraqis directed ICRC team members to the flight suit which was purportedly "found" by a Bedouin boy, but the official Casualty Identification Laboratory Hawaii (CILHI) examination of the suit concluded it showed minimal weathering and adherent soil. We believe the Iraqis planted the flight suit. Near the site where the Iraqis claimed the uniform was "discovered," a few samples of other pilot-related materials were found. Some or all of these items may not have originated in the area in which they were recovered, according to the investigation's results. US Navy experts assessed that the flight suit was the right type and the same size as the suit worn by LCDR Speicher. They also determined that the location and shape of the Velcro used to affix patches was correct for LCDR Speicher and his unit. The condition of the returned flight suit also indicates that the aviator was not in the aircraft at ground impact. Specialists determined that damage to the recovered flight suit indicates exposure to a few seconds of heat. Also, the flight suit showed only a trace of possible blood"
I'm looking forward as to what your interpretation as to what "Occam's razor" says about Saddam handing over a flight suit 4+ years after the fact, claiming it was "recently discovered", and yet forensic evidence doesn't support that fact...
I mean, my interpretation of "Occam's razor" would be that the Iraqis found him, captured him, and gave the US the flight suit to provide the illusion of cooperation...
When he actually died off is anyone's guess...