MonsterQuest was a fun show, even if it didn't produce the greatest documentaries. The 2009 spin-off MysteryQuest opted to use the same format and same narrator (Stan Bernard) to examine questions beyond cryptozoology. They covered topics, including Stonehenge and Nazis, that one would actually expect to find on the History Channel. However, the sensational MonsterQuest format wasn't the greatest to begin with, and the results of MysteryQuest are mixed.
The show did two good episodes about the possible escape of Nazi war criminals after World War II, the first being about Hitler himself. They prove a skull possessed by the Russian government was not Hitler's, which is interesting, although the claim that it was Hitler's wasn't convincing to begin with. They also produce two interesting episodes about Jack the Ripper and the Zodiac Killer, but instead of doing a broad overview and considering many possible options, focus on only a couple possible suspects, Francis Tumblety and Richard Gaikowski. In both cases they accept a bit of hearsay. They have one person who heard the Zodiac talk listen to a recording of Gaikowski's voice; she identifies him as a match, but how valuable is this? She hadn't heard the Zodiac speak in decades, and at any rate she didn't seem to recognize the bulk of Gaikowski's voice, she just thought his "don't worry" sounded like the Zodiac's "good bye." Nevertheless, there's no doubt about it- Gaikowski is a much better suspect than Arthur Leigh Allen.
Other episodes like the ones dealing with Atlantis and alien cover-ups seem to lack much substance; they have some aimless searching for evidence that predictably turns up little. The ghost episode was kind of fun, but it's nothing you can't get from Destination Truth. If the show had lasted beyond ten episodes, it would have been interesting to see how it would evolve. Would it grow more sensational or more serious? That, itself, is a mystery.