I'm not sure how they established that sex, if it did happen, wasn't consensual. But the guy had no alibi, was the last person she was seen with, had her DNA on his genitals.
People shouldn't blame the cops. They don't get anything out of arresting the guy considering that one more open case wouldn't make or break a career, and why would they lie on the stand when their pension, and possibly freedom are riding on it? A detective is likely to have over a thousand cases in their career. They don't take them personally.
Still, I think he should get a second trial if he appeals.