Search for life signal on Titan

The BBC News Website published an article yesterday on the possibility that the methane on Titan has a biological origin, as has been offered as a possibility for Mars' atmospheric methane. Of course, Titan's surface is too cold for life as we know it since water would be as hard as rock at 94 K, but the sub-surface ocean mentioned in the post below (between 300 and 400 kilometers below Titan's surface) might be a possible abode for life that manufactures Titan's methane. While I don't think there is life there, the article does put forth a test by the GCMS experiment on Huygens that can resolve this: the ratio between Carbon-12 and Carbon-13.