In the play The Crucible by Arthur Miller, Rev. Hale finds a witch the year before in his hometown of Beverly. However, the person he believes to be a witch is not, in fact, guilty (as will be the case in Salem).
In the stage notes by Arthur Miller, we learn that Rev. Hale is eager and intelligent. He is pleased to have been summoned to Salem.
This is a beloved errand for him; on being called here to ascertain witchcraft he felt the pride of the specialist whose unique knowledge has at last been publicly called for.
The difficulty, the audience soon discovers, is that Rev. Hale is out of his depth. The author's notes advise the reader that Hale barely has previous experience with a witch.
...he had himself encountered a witch in his parish not long before. That woman, however, turned into a mere pest under his searching scrutiny, and the child she had allegedly been afflicting recovered her normal behavior after Hale had given her his kindness and a few days of rest in his own house.
Hale only gained knowledge of what it feels like to be in the presence a woman that was falsely accused. One might expect that this would be information that could serve him well in Salem, but his eagerness blinds him to the difference between what he wants to see and what he actually sees in the courtroom. By the time it occurs to him to exercise caution, there is no way to stop the madness that takes so many lives in Salem.