A prominent rights organization said on Thursday that the light sentences handed down to 12 men involved in the deadly February attack on an Ahmadiyah community were a result of frustratingly weak efforts made by prosecutors and police investigating the case.

Human Rights Watch in a statement criticized the police and prosecutors, saying they did not conduct a thorough enough investigation, failed to call key eyewitnesses to the stand and erroneously blamed the Ahmadis for provoking the attack.

Three people died and five were seriously injured in the Feb. 6 attack on a small band of Ahmadis by a mob numbering at least 1,000.

"Indonesian authorities should be making all-out efforts to bring to justice those who kill people because of their religious beliefs," said Elaine Pearson, deputy Asia director at Human Rights Watch. "The Cikeusik trial sends the chilling message that attacks on minorities like the Ahmadiyah will be treated lightly by the legal system."

The Serang District Court in Banten found 12 persons guilty on a mixture of charges, including public incitement, destruction of property, maltreatment of others and attacking others causing serious injuries or death. The court sentenced the accused to between 3 to 6 months in prison. Assault resulting in death can bring a maximum penalty of 12 years in prison. None of the defendants were charged with murder or manslaughter.

Much of the attack on the Ahamadiyah home, which involved some 1,500 Islamist militants against about 20 Ahmadiyah members, was captured on video and posted on the Internet. Those videos were cited by prosecutors as a reason to ask for a reduction in sentencing for the defendants, saying that the Ahmadiyah should not have posted the videos online.

"It's outrageous that the prosecutors asked for a reduction in sentences on the basis that the Ahmadiyah filmed and distributed a video of the attack on their community," Pearson said. "It is telling victims of serious crime that they should keep quiet rather than come forward."

One of the Ahmadis seriously injured, Muhamad Ahmad, allegedly told Human Rights Watch that he was not given an opportunity to testify at the trial.

"I might not recognize them, one by one, but I could describe the situation," he said. "We were just trying to defend our properties. Hundreds of Ahmadiyah properties were destroyed and the government did almost nothing."

Pearson lamented what she saw as a clear signal to Islamic militants that the use of violence against minority religions would not be seriously investigated or prosecuted.

"The Cikeusik trial should have been a way to show vulnerable groups in Indonesia that when they are targets of violence, the state will protect them," Pearson said. "Instead, these sentences will embolden militants who will see that using deadly violence brings few consequences."