A person is guilty of a misdemeanor if, believing that an official proceeding has been or is about to be instituted, he destroys, conceals or removes any record, document or thing with intent to impair its availability in the proceeding. SOURCE: G.P.C. § 135: See also § 115a; M.P.C. 241.7; *Cal. § 1104 (T.D. 3, 1969); Cal. § 1144 (1971); Mass. ch. 268, § 6; N.J. § 2C:28-6. COMMENT: Section 52.60 is substantially the same as Penal Code § 135, although it brings the on-set of the crime back in time where the defendant believes that a proceeding is about to be instituted.