Activist Jairo Mora Sandoval in the hatchery of the Ostional beach Leatherback and Pacific Green Sea Turtle Project with fellow volunteers in Costa Rica. (Christine Figgener)

Four men have been found guilty in Costa Rica for the killing of a sea turtle conservationist in 2013. The chief of a three-judge panel said the slaying of Jairo Mora Sandoval, who worked for a green group called Widecast, was tied to his activism in a war “between poachers and environmentalists on the beach.”

In another development in Honduras, the government freed the only eyewitness to the murder of an internationally known environmentalist after holding him for nearly a month.

Those events last week in Latin America, one of the world’s deadliest regions for activists fighting projects such as dams and logging, were greeted as positive by international conservationist groups that are unaccustomed to good news. The reports came as relatives of Berta Cáceres Flores, who was killed early on March 3 in Honduras by gunmen who barged into her home and shot her in bed, traveled to Washington to speak with members of Congress.

In addition, community leaders from Sayaxché, Guatemala, arrived in Washington this week to meet with nonprofit organizations and possibly lawmakers to discuss growing development of indigenous lands by the palm oil industry and death threats against protesters who stand in the way, according to the nonprofit Friends of the Earth.

Protests against palm oil expansion in the Sayaxché region led to the killing of Q’eq’chi Mayan activist Rigoberto Lima Choc in September, the group said. Choc was a schoolteacher who documented a toxic spill and filed a complaint that forced a company to cease operations. A day later, he was killed. There have been no arrests in his killing.

Friends of the Earth is scheduled to hold a public discussion of the palm oil industry and land rights in Guatemala at its Washington office on Friday.

From 2010 to 2014, more than 450 activists were killed in Latin America. Arrests and convictions are rare. Last year in Costa Rica, the men accused of killing the 26-year-old Mora, as well as kidnapping and robbing four foreign volunteers, were acquitted by a court.

But in the surprise last week, the men — Héctor Cash, Ernesto Centeno, José Bryan Quesada and Donald Salmón — were found guilty after prosecutors filed an appeal in the case, which is allowed by the Costa Rican legal system, unlike that of the United States. The four could serve up to 70 years in prison.

The sea turtle conservationist was reportedly taken to the beach, where he was beaten and dragged by a car. A panel of three judges deemed that Mora’s role as an environmentalist for the group Widecast was a key factor for his murder.

“The court rejects that there is any other motive for this murder,” Carlos Álvarez, the trial’s chief judge, was quoted as saying in the Tico Times. “The killing of Mr. Jairo Mora Sandoval was the straw that broke the camel’s back in this war that was taking place between poachers and environmentalists on the beach.”

A woman holds a portrait of Honduran activist Berta Caceras Flores, reading, “It was a political murder.” (AFP/Getty Images)

Gustavo Castro, a Mexican activist and friend of Cáceres, also feared for his life. He was staying overnight at her house in Honduras when the gunmen shot her four times and Castro twice. He said he survived by playing dead. Nevertheless, the Honduran government blocked Castro’s attempt to leave the country after the slaying, arrested him and held him under house arrest at the Mexican consulate for nearly a month.

“What we are confronting are forces very powerful, obscure forces, filled with ambition,” Castro said after arriving home in Mexico, according to Democracy Now, an independent news agency.