In Act II of The Crucible Mary Warren comes home to the Proctor's house after a day working for the courts.  While the Proctor's are upset that she has been there (Elizabeth has repeatedly told her not to go) Mary Warren brings news from town.  Things have escalated.  No longer is it just a matter of a few older women in the town being accused of witchcraft; instead it has become a full trial convicting and executing the women who are torturing the children.

Mary Warren first tells the Proctor's that 39 people have now been accused of witchcraft and of the 39 "Goody Osburn- will hang".  She tells the shocked Proctor's that Deputy Governor Danforth has sentenced her.  Mary Warren also points out that Sarah Good has confessed to witchcraft, and therefore, will not hang. We see here that Mary Warren has changed, and now believes in the work that she is doing as she details the old women sending their spirits out to attack her and mumble curses at her.

Even more shocking is when Mary Warren tell her employers that she saved Elizabeth's life.  She points out that Elizabeth hasn't exactly been accused but instead

Somewhat mentioned. But I said I never saw no sign you ever sent your spirit out to hurt no one, and seeing  do live so closely with you, they dismissed it.

This revelation shows Elizabeth's biggest fear has come true; Abigail is planning on accusing her in order to get to John.