By JACK CHANG

A Brazilian prosecutor has appealed the controversial acquittal of a rancher who had been convicted last year of ordering the murder of U.S. nun Dorothy Stang in the Amazon forest, extending an emotional court case that has made world headlines.

The appeal filed late Thursday in the northern Brazilian city of Belém by prosecutor Edson Cardoso de Souza seeks to cancel Tuesday's acquittal and schedule a third trial for rancher Vitalmiro Bastos de Moura, who was freed immediately after his acquittal.

''We are outraged about the acquittal because it goes against all the evidence the court in the first trial used to convict him,'' de Souza said. ``We're convinced a new trial is necessary.''

De Souza said a panel of judges would decide whether to grant the appeal by year's end. Any new trial would begin early next year.

Since the 73-year-old nun was shot to death in February 2005 in the Amazonian town of Anapu, she has become a martyr for many here who are trying to protect the world's most diverse biosystem from destruction. Her trial also has come to symbolize the immunity of the region's powerful ranchers, who have violently intimidated small farmers eking out a living and activists trying to save the rain forest.

Stang had been trying to create a sustainable-development project on forestland that her supporters said had been protected by Brazilian land regulators. That didn't stop de Moura from claiming the land and other farmers from settling there.

Stang's murder sparked an international outcry, and police eventually arrested two ranchers, de Moura and Regivaldo Pereira Galvao, an alleged intermediary and two alleged gunmen.

The intermediary, Amair Feijoli da Cunha, confessed to receiving about $30,000 to set up the hit, while one of the gunmen, Rayfran das Neves Sales, admitted to using de Moura's gun to shoot Stang six times at close range while she was sitting in the forest reading her Bible.

What has drawn the suspicion of many in Brazil about de Moura's acquittal is that it happened after da Cunha and Sales suddenly changed their stories. Da Cunha said last week that de Moura in fact hadn't hired him, and Sales insisted that he'd acted on his own volition.

De Moura was sentenced to 30 years in prison last year, but Brazilian law calls for an automatic retrial for anyone receiving a prison sentence of more than 20 years. That retrial ended Tuesday night when a jury voted 5 to 2 to let de Moura go.

Human rights activists, environmentalists and even Brazilian President Luíz Inacio Lula da Silva criticized the acquittal, with the president saying Thursday, ''As a Brazilian, as a common citizen, I am obviously indignant about the result,'' although he said he wouldn't interfere with the legal proceedings.

Eduardo Imbiriba, the rancher's lawyer, shot back Friday, saying the president ``hasn't been here and followed the case, and he hasn't seen the evidence.''

De Souza said his office was investigating the bank accounts of Sales and da Cunha, and even of jury members, to find out if someone had paid them off.