Giles Corey comes to court in ACT III to file a deposition that Thomas Putnam is essentially encouraging his daughter to accuse people of witchcraft so that he can claim their land. When someone is tried and convicted of witchcraft, their land goes up for auction and can be purchased at an extremely reduced rate; therefore, if Putnam wanted someone's land, Giles Corey's claim is that he asks his daughter to accuse that person of witchcraft so that he can eventually buy their land:
Giles: My proof is there!
Pointing to the paper. If Jacobs hangs for a witch he forfeit up his property - that’s law! And there is none but Putnam with the; cointo buy so great a piece. This man is killing his neighbors for their land!
Danforth: But proof, sir, proof.
Giles,pointing at his deposition: The proof is there! I have it from an honest man who heard Putnam say it! The day his daughter cried out on Jacobs, he said she’d given him a fair gift of land.
Another important development here is that Giles refuses to reveal the name of the man who told him this information, because he hears that people who have signed the first deposition are being taken into custody. Giles refuses to damn another person to hang, and he is eventually pressed to death because he won't cooperate with questioning. Because he says nothing when asked if he is guilty of witchcraft, his sons are able to inherit his land and his property is not auctioned.