I'm not knocking you or anything...it is just hard to comment on a case or see what point is makes with only some facts.
As I mentioned in my earlier posts, I can see how her failing to admit to sex with someone else could have screwed the case. Other than that scenario, I fail to see how a lack of DNA would factor in the case you describe.
I can't find it online. I'm going to pop over to the PA board and see if anyone remembers it.
At the time, I think the only evidence the police had was (1) the suspects' confessions, which matched, and (2) either witnesses saw them breaking into cars or they were known car thieves or... I can't remember. But the DNA test showed the DNA did not match either suspect, and they were released even before a trial.
If I can find an old article, that should explain it better.