Updated

A man who prosecutors accused of masterminding the killing of two Amazon activists in northern Brazil in 2011 was acquitted by a jury on Thursday.

Jose Rodrigues Moreira was acquitted due to insufficient evidence, said Edmundo Rodrigues Costa, the national coordinator of the Catholic Land Pastoral watchdog group that tracks land-related violence. Costa said prosecutors plan to appeal.

But the panel found two others, Lindonjonson Silva Rocha and Alberto Lopes do Nascimento, guilty of carrying out the killings of the activists. Rocha was sentenced to 42 years and eight months and Nascimento got 45 years. Costa said their attorneys will appeal those rulings as well.

Jose Claudio Ribeiro da Silva and his wife, Maria, were gunned down near a reserve in the jungle state of Para, where they taught farmers how to use land in a sustainable manner. Para is among Brazil's most violent and lawless states, notorious for land-related violence, contract killings, slave-like labor conditions and wanton environmental destruction.

"The verdict was to a certain point a positive one because those who shot the guns were convicted," Costa said. "But the verdict unfortunately again showed that those who order people killed enjoy impunity."

Phone calls to the courthouse in the city of Maraba, where the trial was held, and to the local prosecutor's office, went unanswered.

The Silvas had reported illegal loggers to police and federal prosecutors, and confronted powerful interests that destroy the forest to sell timber, or to clear land for cattle or soybeans.

Prosecutors accused Moreira of ordering the killings because the Silvas opposed the eviction of three families occupying his land in the Nova Ipixuna reserve.

Last month, the Land Pastoral said the number of rural activists killed in the country rose 10 percent from 2011 to 2012, with most deaths occurring in the Amazon region.

It said in a report that illegal logging and the resulting conflicts were responsible for the majority of the 32 slayings of local activists in Brazil last year.

The Land Pastoral group says 1,566 rural activists were killed in Brazil from 1985-2012.

In Brazil, killings over land are common and seldom punished, as powerful landowners clash with farmers and others for control of lucrative farming and logging land.

The slayings are mostly carried out by gunmen hired by loggers, ranchers and farmers to silence protests over illegal logging and land rights in the environmentally sensitive region.