Wrong! Lack of evidence "proves" nothing. This logical error is becoming more and more common these days but it is still a fallacy. In formal logic it is called the "fallacy of the negative premise".
In the syllogism above the lack of evidence may just as well be due to care taken by the accused to eliminate such evidence. You can argue till you're blue in the face but you cannot make a solid case either way.
Putting it another way is that "lack of evidence" is just that, a lack of evidence, which proves nothing at all, inferring anything else from that is a jump from solid ground into the darkness. Conclusions drawn with the aid of logic are built up piece by piece of demonstrable evidence and held in place by rigid rules making the conclusions drawn irrefutably correct. There is no place for intuition, common sense, or unsupported assertion.
Regards,
GtG
If you look at many of the child sex abuse cases of the 80s, especially including this one, and, although not of the 80s, the infamous Duke rape case, lack of certain types of evidence is clear proof that the alleged abuse didn't occur.
For example, in the case covered by the article, "Among other problems, prosecutors withheld medical exams that showed no evidence of abuse, even though Krause claimed the abuse was repeated and violent." It being very hard to conceal physical evidence of "repeated and violent" abuse, the lack thereof is clear evidence no such thing happened, much as the lack of a knife wound in an alleged stabbing case would be strong evidence that no stabbing occurred.
The original allegations in the Duke rape case were detailed and lurid; however, no DNA or other physical evidence of the type that could be expected in such a case was ever found; hence, the lack of normally expected evidence became compelling evidence that the case was a fabrication.