Way back in 1968, a 1.8m, hairy, non-human "corpse" was first exhibited in a Minnesota carnival. It made a big stir in the then-nascent business of cryptozoology, especially when zoologist Bernard Heuvelmans named it a new species after he and Ivan Sanderson had spent considerable time observing and photographing it through the ice block in which it was maintained.
Despite the interest, or maybe because of it, the "original" creature was "replaced" (according to showman Frank Hansen) with a model, and then vanished entirely. No one has seen any sort of Iceman exhibit for four decades.
Some cryptozoologists still think the original was a genuine unknown primate, while others dismiss it as a fake from the beginning (a view to which Sanderson eventually subscribed). Hansen told several different stories about the thing's origin and now refuses to discuss it at all.
The single most interesting question to me concerning the Iceman isn't what it was, but where is it?
If it was a genuine animal, there's no sensible reason for some collector to be keeping it unviewed in a freezer, not when modern media would ensure a big payday for revealing it (even if the importance to science did not motivate said owner).
If it was a fake from the beginning (as I think likely), it was a good fake, made up with some care (and cost), so why not bring it out of storage now and let the highest bidder publicize the solution to the mystery? (OMNI magazine once named the late Disneyland model-maker Howard Ball as the craftsman.)
Even if there was both a real animal and a fake, there still seems no reason to be keeping either one sequestered.
Suppose for a moment the animal was real. If it was a corpse that was illegally imported, that would have explained some secrecy and obfuscation, but the statue of limitations concerning any crimes involved lapsed a long time ago. (Even if it was provably Vietnamese, as Heuvelmans once theorized on the basis of no particular evidence, the worst thing that could happen is that Vietnam could officially ask for it back. The US government wight well agree, but the owner would have already made his big payday from the American media, so - so what?) If it was an animal killed in the US, any legal sanctions that might apply for killing an animal for which no hunting season existed have likewise long since lapsed. The only statue that never runs out is murder, and, whatever the thing was, one point of universal agreement is that it was not Homo sapiens sapiens, the only creature covered under any murder statute anywhere in the world.
I suppose it's possible that, fearing legal trouble, the owner might have dumped the original exhibit (whether a corpse or a model) a long time ago. If so, I'm sure he's kicking himself for that after seeing what the tabloids will spend for an exclusive story these days. (Hansen went back and forth on whether he owned it or was showing it for a mysterious wealthy individual (who would have had WHAT motivation, exactly, for letting a carnival drag his priceless scientific treasure around for 25 cents a look?))
There are cases where expensive art objects have vanished and are in the illegal hands of some irrational rich person who does nothing but admire the work and cherish the fact that only he will ever see it. That seems pretty way out for a dead animal and ridiculous for a fake one... but you never know with humans.