CASPER (AP) — A federal grand jury has indicted an Oklahoma City man accused of posting online threats to commit acts of violence in the central Wyoming city of Casper.

Federal officials say Glenn Allen Kirkham authored a Jan. 14 online message board posting that threatened to employ nontraditional weapons to prove that a "high score" could be achieved without assault rifles.

The message mentioned Casper but did not specify a specific target or location.

The Casper Star-Tribune reports that court documents say Kirkham told investigators the post was a "work of artistic falsehood."

Kirkham is charged with transmitting a threat by interstate communications. The offense could carry a sentence of up to five years in prison and a $250,000 fine.

Kirkham is free on a $5,000 unsecured bond.