Just because the DNA evidence has not been tested doesn't mean there's been no action on the case...In several instances, men were tried, convicted, and sent to prison long before it's existence was even revealed to the defense. Ricardo Rachell's case comes to mind. In Gilbert Amezquita's case, the judge denied the defense's request to allow DNA evidence to be presented at court. Both these men were exonerated and freed after serving many years in TDCJ.
Anybody facing the death penalty probably ought to let the prosecution take a DNA test.