If your question is can, in the USA, someone be found guilty on the basis of witness testimony alone without physical evidence, the answer is yes. Whether this happens depends upon the nature of the crime, how many and how convincing the witnesses are, and how convincing the defendant is. It is believed that the judge and jury are mislead by witnesses rarely; but, in theory it must happen from time to time.
If you have strong reason to believe your daughter was wrongly convicted you should pursue the matter. You will have to consult your lawyer about how to proceed. You would have to have strong evidence of wrongdoing by the prosecution or recanting by the witnesses to get anywhere.
You need to consult a lawyer if you believe justice has not been done. But, as far as your basic question goes, the answer is that a person may be found guilty on witness testimony alone. It is up to the judge and jury who to believe.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.