Try PCR, perhaps.
I know that both the FBI and Lifecodes Labs have reported difficulties in
analysis of DNA recovered from bloodstains specifically on blue denim fabric,
but beyond noting the difficulty (poor yield, increased degradation), these
groups have not, so far as I know, said anything about what the basis of the
difficulty might be or how it might be circumvented.
By the way, isn't it a bit late in the day to be worrying about factors that
might confound DNA typing? All the local forensic theologians are very holy
about how their in-advance validation studies have allowed them to identify
and avoid these kinds of problems. And anyway, even if you now come up with
some sort of ad hoc fix that yields a DNA typing pattern, what scientific
basis do you really have for saying that the pattern can be interpreted in
the same way, and with the same kind of confidence, as patterns produced in
the absence of the ad hoc fix (i.e., with your standard recipe)?
NYU Medical Center
New York NY USA
peter at mcbcm2.med.nyu.edu