A Bahraini court sentenced two policemen to 10 years in jail on Tuesday for torturing to death a Shiite protester, and acquitted three others of lesser charges, a judicial source said.
The pair were convicted of "torturing to death Ali al-Saqr... following his arrest during the uprising in February 2011," the source said.
The other three, facing charges of "failing to report the crime," were acquitted.
All five were acquitted on charges of killing another protester, Zakeriya al-Asheeri, who died in detention in 2011.
Bahrain's largest opposition bloc, Al-Wefaq, criticised the ruling, claiming that "the brutality by which Asheeri was killed was caught on camera."
It accused the courts of "a series of untrustworthy verdicts that have become part of a no-punishment policy the regime is implementing for its executioners."
The verdicts "affirm the need to bring high-ranking officials to justice," the Al-Wefaq statement said, calling for "a fair and independent judicial system based on transparency."
In February, a court acquitted two policemen charged with shooting dead a Shiite protester two years ago.
And a month earlier, a court sentenced a policeman to seven years for torturing a protester to death during month-long Shiite-led protests in Manama against the rule of the Sunni Al-Khalifa dynasty.
A number of others 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 inquiry appointed by the king that confirmed allegations of excessive use of force by security forces during the unrest.
Separately, state news agency BNA reported that six people have been referred to the public prosecution for "exploiting online social networks to insult and defame the king," without giving further details.
Home to the US Fifth Fleet and strategically situated across the Gulf from Iran, Bahrain has continued to witness sporadic Shiite-led demonstrations, now mostly outside the capital.
A new round of talks between the opposition and the government began last month against the backdrop of daily protests launched around the second anniversary of the pro-democracy uprising.
But the dialogue has been dogged by disagreement as the opposition insists that representatives of the king, and not only the government, should take part.
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.