A little history for y'all. In World War II, servicemen who were captured generally were not promoted while they were in captivity. It was the same way in Korea and other previous wars. There was generally not that much a problem with it until the Vietnam War, simply because the previous conflicts that we were in did not last as long as the Vietnam War (for the second longest, you have to go back to the Revolutionary War).
From the time that Eddie Alvarez was shot down in the summer of 1964 to when the last POW's were released by North Vietnam it was over EIGHT YEARS! Due to the length of their captivity, the hardship on their dependents and basic fairness the military kept promoting them at the time their peers were up for promotion (I believe their dependents were paid the salary). I think that Alvarez went in as a LTJG and came out a LCDR or CDR (not which one, he retired at CDR).
Please be aware, I am doing the following from memory so there may be a few small discrepancies, please let me know if I get any of the details wrong:
The DOD designated LCDR Speicher a KIA a day after he was shot down on the first night of the war. The designation was apparently questioned at the time by some of his fellow aviators in his Airwing due to the lack of evidence that he was dead, they had no body. There is even some dispute on how he died, he may have apparently been shot down by a MiG-25 Foxbat (it was seen on radar and visually in afterburner by several other members of the Airwing about the time and in the same vicinity of where Speicher went down). The crash site was not found at the time and his body was still missing at the end of the war.
A couple of years later (1994/5?) a Qatari Major was falconeering in the desert of Iraq when he came across the wreckage. He told the US about the crash site and we requested Iraq to take a look at it and were allowed a year later. The crash site had been obviously tampered with in the intervening year (the Qatari Major had given a pretty good description and pictures? of the site and some obvious stuff was missing or had been moved) and Speicher's body was not found. The Iraqi's handed over what they claimed was his flight suit but we found no evidence that it was.
The Navy decided to redesignate LCDR Speicher Missing/Captured in 1999? and he was promoted as a POW would be. A special team went in to look for Speicher after OIF and unfortunately found no conclusive evidence of his fate (I work some of the guys who assisted the team). There were some eyewitness reports from other prisoners held in Iraq in the 90's but they have not been verified.
That is where it stands right now.
ie rumor mill. From what I've read about Speicher, a Mig-25 shot him down.