Neb. Rev. Stat. § 28-922

(1) A person commits the offense of tampering with physical evidence if, believing that an official proceeding is pending or about to be instituted and acting without legal right or authority, he or she: (a) Destroys, mutilates, conceals, removes, or alters physical evidence with the intent to impair its verity or availability in the pending or prospective official proceeding; or (b) Knowingly makes, presents, or offers any false physical evidence with intent that it be introduced in the pending or prospective official proceeding. (2) Physical evidence, as used in this section, shall mean any article, object, document, record, or other thing of physical substance. (3) Tampering with physical evidence is a Class IV felony, except that if such offense involves a pending criminal proceeding which alleges a violation of another offense classified: (a) As a Class II misdemeanor or a lower classification or a violation of a city or village ordinance, the offense is a Class I misdemeanor; or (b) As a Class II felony or a higher classification, the offense is a Class II felony.