Patricia Cornwell (writer also used to be a coroner) spent her own money to do DNA studies on Jack the Ripper.
One problem they had was when they collected the DNA they put it in a plastic sleave and heat sealed it. The probem she had with the DNA was the HEAT DEGENERATES THE DNA.
Dont they use heat in dry cleaning? If so how could they possibly have gotten a good sample of DNA off of Westerfields jacket?