Any public officer or employee, who knowingly does any of the following, commits a class “D” felony:
1. Makes or gives any false entry, false return, false certificate, or false receipt, where such entries, returns, certificates, or receipts are authorized by law.
2. Falsifies any public record, or issues any document falsely purporting to be a public document.
3. Falsifies a writing, or knowingly delivers a falsified writing, with the knowledge that the writing is falsified and that the writing will become a public record of a government body.
4. For purposes of this section, “government body” and “public record” mean the same as defined in section 22.1.