Perhaps fraudulently altered would convey the meaning you are trying to put across.

It would cover both the motive and the act.

Many forged things are fair copies of the original where this is specifically not a direct copy.

Perhaps fraudulently altered would convey the meaning you are trying to put across.

It would cover both the motive to deceive and the act of modifying the document.

Many forged things are fair copies of the original where this is specifically not a direct copy.

The Legal Information Institute writes an alteration fraudulently made discharges a party whose obligation is affected by the alteration, and in A Digest of the Laws of the State of Georgia and Acts Passed by the General Assembly of Georgia we read If any person ... shall falsely and fraudulently alter ... note, ... such person ... shall ... be punished