DAs are mostly concerned with saving their sorry asses as well as their jobs, not with the truth. There are some good ones out there, but they are few and far between.
Similar comments were made to the press after the charges against my fiance were ....I can never remember the word...not dropped, but not processed (it's a French word). "Well, we don't know it (repeated incest) did not happen. We have no reason to believe she's lying."
Oh, really? How about the fact that she changed her story every time she told it and there was absolutely no physical evidence?
In the end, everyone knew she was lying but couldn't, "of course", come out and say so.