In the Salem witch trials, or any other witch trials, was a woman ever found innocent? What evidence was presented to determine this?

Some really good stuff has been done on the Salem Witch trials, which you can find below:

(Late edit: as u/sunagainstgold has correctly observed, I am only speaking about the exceptional events in Massachusetts during the seventeenth century. See that post for a more well-rounded examination)

To get at your question specifically, the answer is actually a little difficult. Far more women [AND MEN lest we forget the men were accused, questioned, tortured, and executed as suspected witches] were accused of being witches than ever were put on trial. So in a sense, I suppose you could say that people accused of being witches but never put on trial could be considered innocent. That the accusations didn’t stick was itself a form of exoneration. Once a person was put on trial, however, being found “innocent” was not really an option. The key to understand is that the “trials” are not like a modern criminal trial. If a person was put on trial for witchcraft, in all likelihood, the only options were to confess or not confess and therefore be found guilty. No “witches” who confessed (process explained a bit at the end) were executed. Although these women did receive punishment, often in the form of banishment that could itself be a death sentence of sorts, I suppose you could see confession as a form of exoneration, at least from the penalty of death.

Let me just provide a little historical context here that will explain the answer a bit. Historians have put forth a plethora of explanations for the witch craze that struck New England during seventeenth century; however, among the most plausible, I believe, are the studies that address occurrence as a social phenomenon. Accused witches were probably targeted because of their position in society (especially landed widows), their role as midwives, or even possibly due to their race. It is also possible that many accusers had suffered psychological trauma that led to their distressed state in naming “witches.” This would explain why the witch craze was not isolated to only one small town or section of a town as could be expected if it were due to an ergot contamination or some other event of mass hallucination. (Sorry, the “drugged theory” is sexy, but it just doesn’t seem to add up!)

It’s likely the many people used witch accusations to target enemies or vulnerable members of society. Because accusing someone of being a witch could work in your favor, during the witch craze, there were men and women publically accused of being “a witch” that never found themselves brought before the political/religious leaders of the Puritan community. That these charges didn’t stick are indication that these men and women accused were held in high enough regard by other members of the community to avoid a public trial and the shame of confession. Like I said before, I suppose you could see these people as exonerated.

Once a person was placed “on trial,” however, the only real possibility was confession or being found guilty. I won’t go into a lengthy explanation about why a person would or would not confess, but the statistic holds true that no person who confessed to “witchcraft” was executed because confession also included repentance and, to prove your redemption, often the naming of more witches! You can see how the craze continued.

TL;DR: After being placed on “trial,” there was little to no chance of being found innocent. There were accused members of society who were never placed on trial and so you can consider these people exonerated.

Sources:

Demos, John Putnam. Entertaining Satan: Witchcraft and the Culture of Early New England. New York: Oxford University Press, 1982.

Karlsen, Carol F. The Devil in the Shape of a Woman: Witchcraft in Colonial New England. New York: W.W. Norton, 1998.

Stout, Harry S. The New England Soul: Preaching and Religious Culture in Colonial New England. New York: Oxford University Press, 1986.