A prima facie case of a violation of this article shall be established upon the showing that any person charged with the violation of the section was found, seen, or arrested in any public school buildings or upon public school grounds in the city. Upon such showing, the burden of proof shall be upon the accused to show such person’s lawful business or excuse for going or being in any public school building or upon any public school grounds in the city.
(Sec. 13-5.3, R.O. 1978 (1983 Ed.)) (1990 Code, Ch. 41, Art. 32, § 41-32.3)