BUNNELL, Fla. -

An internal affairs investigation is underway to determine whether any Bunnell police officers took part in an exchange of messages about slain teenager Trayvon Martin that led to the firing of a Volusia County beach officer.

Bunnell City Manager Armando Martinez told the Daytona Beach News Journal a case regarding Trayvon Martin messages is open.

Neighborhood watch volunteer George Zimmerman fatally shot Martin in February 2012 and was acquitted of murder charges in July.

Last week, the department also launched a strict social media policy that bars officers from sharing material that is "unprofessional, unbecoming, illegal, unethical, sexual, violent, harassing, racist, sexist or ethnically derogatory."

Volusia Beach Safety Officer Todd Snipes was fired three weeks after the verdict for posting messages about the case on social media.