Is it permissible to take a person's property documents from his father without his knowledge and photograph them, then give a copy of them to this person's wife to help her in her case against her husband who claimed not to own any property, in order to repel injustice and reveal the truth, or is this action considered haram and theft?

A person must fulfill trusts, for Allah has commanded it and forbidden betrayal, which is one of the characteristics of hypocrites, as stated in the Hadith: "The signs of a hypocrite are three: whenever he speaks, he tells a lie; whenever he promises, he breaks his promise; and whenever he is entrusted, he betrays." And "There is no faith for one who has no trust, and no religion for one who has no covenant." Therefore, it is not permissible for your father to give the trust documents to anyone other than their owner, nor is it permissible for you to take a copy of them and give it to the man's wife. This is aggression, abuse, and disobedience. The man might be justified in concealing his property to avoid an unjust ruling. If the woman is righteous in her claim, she can prove it with the testimony of witnesses.