The simple matter is that if there is an unknown ape out there then the DNA studies would have turned it up. Paulides uncovered many results that showed human prior to the Ketchum study. It really shouldn't be so tough in this day and age to come up with the samples or find that unique DNA sequence that would show an uncatalogued ape.
Bigfoot enthusiasts aren't the only ones collecting samples either, so it seems to me that if bigfoot does exist, it must be masquerading as us to have hidden from us so well. It makes some sense for the samples that turn out human or assumed contaminated, and the fact that if they were human of some type, their found bodies would be handled differently than just some animal.
They are probably better off living their secret lives if we can't just accept them for what they are, and it's really just too bad that someone would have to commit murder to find this to be true with potentially not having control of the specimen once found to be human, and facing the delima of self disclosing murder or remaining silent with no evidence which would leave leave us all to bear this repeating scenario over and over again.