FALSELY COMPLETES

A person "falsely completes" a written instrument when

(he/she), by adding, inserting or changing matter, transforms an incomplete written instrument into a complete one, without the authority of anyone entitled to grant it, so that such complete instrument appears or purports to be in all respects an authentic creation of or fully authorized by its ostensible maker or drawer; or
(he/she) signs (his/her) own name to a written instrument, thereby falsely and fraudulently representing that (he/she) has authority to sign the instrument.

Source: General Statutes § 53a-137 (5) (applies to Part X: Forgery and Related Offenses, §§ 53a-138 -- 53a-145).