(1) A person commits the offense of forgery when, with purpose to defraud, the person knowingly falsely signs, makes, executes, or alters any written instrument.

(2) A purpose to defraud means the purpose of causing another to assume, create, transfer, alter, or terminate any right, obligation, or power with reference to any person or property.

(3) Except as provided in subsection (4) of this section, forgery is a Class C offense.

(4) If the forgery is part of a common scheme or plan, or if the value of the property, labor, or services obtained or attempted to be obtained exceeds $1,000, the offense is a Class E offense.