http://www.space.com/scienceastronomy/060323_meteorite.html

That being the case (them being unable to extract DNA from the tunnels), there are two likely scenarios.

"One is that there is an abiotic [non-living] way to create those tunnels in rock on Earth, and we just haven't found it yet," Fisk said. "The second possibility is that the tunnels on Martian rocks are indeed biological in nature, but the conditions are such on Mars that the DNA was not preserved."

Apparently they don't consider a third scenario, in which the tunnel critters were alife but not based on 'Earthly' DNA. Seems a bit narrow minded to me.

The (w)hole thing could be contamination anyway I guess.

If so, they would probably find DNA

Is it just me, or does it seem like the Mars meteorite researchers are really reaching?

Not to disparage the research or the personnel involved, certainly, but the ubiquitous nature of life on Earth--especially microbes--seems to argue that Martian life (DNA-based or not) would also leave unmistakable evidence of its existence in these meteorites. Any announcement of putative life signatures should be restrained until strong corroborating evidence is also available.

There's the old old old story about a Pastor's note in the margin of his sunday sermon: "Weak arguement. Raise voice for emphasis."