A Brazilian court has convicted a third man in last year's killing of an American nun who spent decades defending land rights for poor settlers in the Amazon.

A judge in the Amazon city of Belem Thursday sentenced Amair Feijoli da Cunha to 18 years in prison. He was found guilty of serving as an intermediary between two local ranchers accused of ordering the murder of Sister Dorothy Stang, and two men who carried out the killing.

The gunmen have been convicted of murder. The ranchers were charged last year but have yet to be put on trial.

Sister Stang, 73, was shot to death in February 2005, near the town of Anapu in northern Brazil. She was a well-known activist for rain forest preservation.

Some information for this report was provided by AP and Reuters.