A Bahraini appeals court on Sunday reduced a seven-year jail term handed down to a policeman accused of killing a Shiite protester in 2011 to six months, a judicial source told AFP.
In a separate case, the court acquitted two other police officers who had faced charges of killing another protester, the same source said.
The first officer was sentenced in January to seven years for beating a Shiite protester to death, and the two others were acquitted of shooting dead a demonstrator in November 2011.
The court also confirmed jail terms for 19 Shiite protesters who were sentenced to five years in prison each for attacking policemen.
A number of police officers are being investigated or are on trial for allegedly torturing detainees after hundreds of Shiites were rounded up when security forces crushed the protests in March 2011.
The authorities say they are implementing the recommendations of an independent commission of enquiry appointed by the king that confirmed allegations of excessive use of force by security forces during the unrest.
Home to the US Fifth Fleet and strategically situated across the Gulf from Iran, Sunni-ruled Bahrain has continued to witness sporadic Shiite-led demonstrations, now mostly outside the capital.
The International Federation for Human Rights says around 80 people have been killed in Bahrain since the violence first broke out on February 14, 2011.