Chief Prosecutor Nawaf Abdullah Hamza said a criminal court issued a ruling against an unnamed police officer arrested in connection with the death of protester Ali Abdul Hadi Mushaimaa.
"Details of the incident indicate that the defendant was a member of the security units in al-Daih area in February, and during dealing with one of the rioting cases in the area, he fired bullets from his rifle at the victim causing him injuries (that) led to his death," the prosecutor was quoted by the official Bahrain News Agency as saying.
Bahrain has faced criticism for a crackdown against an opposition movement that grew out of the Arab Spring movement in early 2011. Dozens of Bahraini demonstrators were killed during an uprising against the Sunni monarchy that year.
Since then, the government said it was committed to reforms outlined by an independent panel of inquiry investigating 2011 unrest. Last month, the monarchy said it was launching a national dialogue as part of the reform efforts.
Human Rights Watch this week said much of the reform rhetoric was window dressing. In late 2012, the government placed a temporary ban on protests and revoked the citizenship of several opposition leaders.