A suspect in the killing of an American nun, who spent decades trying to protect the Amazon (search) rain forest and its poor residents from loggers and ranchers, has surrendered to police, authorities said Saturday.

Amair Freijoli da Cunha was taken into custody after turning himself in to police in Altamira (search), a city about 80 miles from where Dorothy Stang, a 73-year-old member of the Sisters of Notre Dame de Namur (search), was shot dead Feb. 12, police said.

Stang originally was from near Dayton, Ohio.

Authorities still were searching for two purported gunmen and a rancher accused of ordering the slaying, police investigator Ana Indira Vaz said. Arrest warrants for Cunha and the three other suspects were issued Monday.

Cunha allegedly hired the accused gunmen, police said, and was the intermediary between the killers and rancher Vitamiro Goncalves Moura, who authorities say ordered the killing.

Cunha was accompanied by a lawyer when he turned himself in, police said. Cunha admitted knowing Moura but denied being involved in Stang's killing, police said.

Also Saturday, police released a photograph of suspected gunmen Rayfran das Neves Sales, who was identified by witnesses, police said.

About 50 state and federal officers and jungle troops in helicopters and pickup trucks were hunting for Neves and the other suspects in the largely lawless Amazon region where Stang was killed.

"It's just a matter of time before we catch them. We're close," Vaz said.

Walame Fiado Machado, who is heading the federal police investigation, said recently he believed the two gunmen were probably hiding in a dense, remote stretch of forest near Bida's ranch. He said the rancher and an associate may have fled the region in a small plane soon after the shooting.

Stang was killed at the Boa Esperanca settlement, near the rural town of Anapu, about 1,300 miles north of Rio de Janeiro.

Stang, a naturalized Brazilian, had been in the region for more than 20 years helping protect the Amazon rain forest and local peasants.

Lawlessness has long been common in Para state, where ranchers, backed by hired gunmen, ensnare poor workers in an endless cycle of debt akin to slavery.

In Sao Paulo, about 1,000 people attended a mass in Stang's honor celebrated by Cardinal Claudio Hummes.