In Act Three, we learn that Rebecca Nurse has already been convicted of witchcraft on the evidence given by the girls. We also learn a bit more about how incredibly well-respected Rebecca (and Martha Corey and Elizabeth Proctor) are in the town as well. John Proctor, Francis Nurse, and Giles Corey present a document, a "sort of testament," signed by ninety-one people who all attest to their women's good characters. These people swear that they have known these women for many years and have never seen any indication that they have had any association with the Devil. For these individuals to risk themselves by signing the document being submitted to this corrupt court indicates just how well-respected and loved the women are in their town. Rebecca, especially, is so holy that Mr. Hale could identify her by sight in Act One, as a result of her peerless reputation, and the townspeople's willingness to commit themselves to her defense seems to confirm her goodness.
Well, in Act II we learn that Rebecca has been accused of witchcraft, specifically the supernatural deaths of Goody Putnam's children. We learn that she has been arrested and is being taken to jail along with Martha Corey and now Elizabeth Proctor to await trial.
In Act III Rebecca's husband, Fancis, attempts to convince the court that Rebecca and the others are innocent and that Danforth is being deceived by the girls. By the time he returns to the court with documentation to support his claim, Rebecca and Martha have already been tried and found guilty of witchcraft.
Proctor brings a long list of 91 character witnesses who support Rebecca and Martha and petition the court for their release. This tremendous show of support proves again how much Rebecca and Martha are respected in the community.
Francis is upset when all 91 character witnesses are called in for questioning by the court since he personally promised them that no harm would come from their signing his petition.
You can find an excellent summary of The Crucible at the link below: