BRASILIA, Brazil - Brazilian police searched Amazon jungle on Sunday for suspected killers of a 74-year-old American nun gunned down after defending peasant farmers in conflicts with loggers and ranchers.

Two gunmen shot and killed U.S. Catholic missionary Dorothy Stang at a settlement of landless peasants on Saturday, 30 miles from the town of Anapu in northern Brazil's Para.

Dorothy Stang, a 74-year-old American nun, was shot to death early February 12, 2005 in Brazil's Amazon rain forest where she worked to defend human rights and the environment despite frequent death threats, federal police said. Unknown assailants shot U.S. missionary, Dorothy Stang at point-blank range at an isolated agricultural settlement in dense jungle 31 miles from the town of Anapu in the state of Para, police and fellow religious workers said. A February 12, 2004 file photo shows Missionary sister Dorothy Stang in Belem, northern Brazil. REUTERS/Imapress/AE/Carlos Silva

Stang, a native of Dayton, Ohio, spent three decades backing small farmers in Amazon land battles and faced death threats.

Police identified the gunmen and suspect a local rancher ordered the killing, Human Rights Secretary Nilmario Miranda told Reuters by phone from the Anapu region.

"Everything indicates this, the gunmen's links, the history of (killing) contracts around here," said Miranda, adding that police did not yet want to give the name of the suspect.

Hours after Stang was killed, a worker on a ranch adjacent to the settlement was shot and killed in front of his wife and five children by eight armed men, police said.

Brazilian President Luiz Inacio Lula dispatched federal police teams to investigate the deaths, which have highlighted the land battles raging in the Trans-Amazonian highway region, about 435 miles southwest of state capital Belem.

The settlement where Stang was killed is linked to a vast, state-run sustainable development project. Loggers and ranchers are encroaching on the area set aside for small farmers.

Stang, known as "the angel of the Trans-Amazonian" to supporters, and "the terrorist" by ranchers who opposed her, encouraged small farmers not to flee or sell.

Anapu ranchers accused her of supplying guns to peasant farmers. Fellow missionaries in the Sisters of Notre Dame de Namur order, which has some 2,000 nuns spread across five continents, dismissed the claims as "absurd and false."

Stang's death came nine days after she warned Miranda of death threats to her and local farmers as he set up a program to defend human rights workers in Para state.

"They did nothing to protect Dorothy," said Antonio Canuto, a leader of the Pastoral Land Commission, the Catholic rights group she worked for. "This government protects big farmers."

Lula promised to settle 400,000 landless families during his four-year term to even out Brazil's wealth inequalities. He is way behind target.

Para has Brazil's highest rate of deaths connected to land battles, accounting for more than 40 percent of 1,237 murders between 1985 and 2001, according to environmental group Greenpeace.

Federal officials said they did not expect Stang to become a victim. She was a public figure who was known nationally after winning awards for human rights and environmental work.

Miranda said local landowners felt threatened by her as she gained increasing government support for her work.

He said her death intensified the government's will to expropriate illegally occupied land and turn it into landless settlements and reserves.

"We're going to show creation of these reserves and agrarian reform is irreversible," said Miranda.

Additional reporting by Leonardo Pedro in Belem

© 2005 Reuters Ltd.

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