If the dogs detected the remains of a cadaver they were sensing the still-extant chemicals typically given off by a decomposing body called cadaverines. Cadaverines include carboxylic acids, aromatics, sulfurs, alcohols, nitro compounds, aldehydes and ketones. Most of these chemicals are relatively small molecules with as few as 4 atoms each. But it is amazing that even these molecules remain detectable at the site after 80 years.
For DNA it is a different story. Each "letter" or nucleotide (C, G, A or T) in a strand of DNA has 13 or more atoms, and it takes between 76 and 80,000 pairs of them linked together to create a single gene. So simply to detect DNA we are looking for molecules (or at least parts of them) that are a multiple orders of magnitude bigger than a cadaverine molecule. And very large molecules like DNA are much more fragile than small ones. Entropy, you know.
It seems unlikely to me that we will be successful in detecting DNA in the samples, never mind associating the DNA with a single individual, but we can hope.
Jon