oops, same thing.
I was thinking probabilities.
In any case, the number makes the "experts'"assertion totally ridiculous. Even if there was a 20% chance of NO DNA and an actual rape, the probability is less than 1% that a person was raped by 3 people and there was no DNA. On the other hand if there was no rape there is a 100% chance that there would be no DNA of the APs!!