A Brazilian rancher has been convicted of ordering the murder of an American nun for her defence of the Amazon rainforest and its peasant farmers.

In a rare case of justice served, landowner Vitalmiro Bastos de Moura was given the maximum sentence of 30 years by a court in the Amazonian state of Pará for masterminding the shooting of Dorothy Stang in February 2005.

Moura denied the charge. His defence lawyer said that Sister Dorothy, 73, was responsible for her own death because of her “criminal actions” in supporting the region’s poor.

Originally from Dayton, Ohio, Sister Dorothy was a naturalised Brazilian who fought for the rights of poor farmers in the Amazon rainforest against the intimidation and violence of loggers and ranchers in a struggle over land that has claimed hundreds of lives.

Of nearly 800 killings linked to land disputes in Pará in the past 30 years only four people have been convicted of ordering killings, as opposed to poor pistoleiro gunmen who carry them out, and none of these four is in jail.

During sentencing the judge said that Moura was “a violent person, unsuited to living in society because of his greed” and that he hoped his conviction would lead to another rancher accused of involvement being convicted when brought to trial. Regivaldo Galvão is also accused of engineering the killing.

Moura’s prosecution was seen as a test case of Brazil’s commitment to cracking down on lawlessness in its Amazonian region. Since the military Government promoted the opening up of the Amazon in the 1970s in the vast but sparsely populated region it has attracted millions of Brazilians looking to make their fortune or, in the case of landless peasants from other regions of Brazil, to carve out a plot of land that they can call their own.

For decades loggers and ranchers have used forgery or corrupt purchase of land titles and the connivance of local politicians and police to grab huge tracts of the forest, which they exploit ruthlessly for timber and cattle. They quickly resort to violence when small subsistence farmers get in their way.

Moura was accused of ordering the killing of Sister Dorothy and paying an intermediary to hire two gunmen to kill her for 50,000 reais (£12,600). The gunmen, convicted in an earlier trial, confessed originally that they had been hired by Moura and the jury ignored a later contraction.

Sister Dorothy’s 70-year old twin brothers celebrated with supporters outside the court after the judgment. “Today we are very happy because we got justice. Now we are waiting for the trial of Taradão,” said her brother, David. Local human rights groups said that the conviction was an important milestone in ending judicial impunity for ranchers in the region.

The killing of Sister Dorothy shocked Brazil’s Government into asserting more control over its unruly Amazonian region. It quickly sent in the Army to try to clamp down on violent land disputes and created several huge new reserves to protect the jungle from deforestation.

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