Mr. Baldenegro won the Goldman Prize in 2005, the year after he was released from prison, where he had spent 15 months on weapons and drug charges that were eventually thrown out.

In 1993, Mr. Baldenegro formed an advocacy group and began organizing sit-ins and marches to force the government to suspend logging licenses, according to the Goldman Prize. But despite early victories, the government continues to grant concessions, Ms. González said. Legal cases filed by the Tarahumara to assert their rights over their ancestral lands have been stuck in court for decades, she said.

The violence in the region has intensified since the government’s campaign against drug cartels began at the end of 2006. Local bosses known as “caciques formed alliances with drug traffickers, which provided them with hit men,” she said.

Many of the Tarahumara, including Mr. Baldenegro and his family, were forced to leave their communities before the threat of armed men who arrived to clear the forest and plant marijuana on the deforested mountainsides.

Over the past six years, he had been working with a “very low profile,” Ms. González said. In the last year alone, four other activists in the same municipality, Guadalupe y Calvo, have been killed, she said.

Susan R. Gelman, president of the Goldman Environmental Foundation, called on the Mexican authorities to find Mr. Baldenegro’s killers and bring them to trial. “Unfortunately, too many governments are failing to create safe spaces where people can voice their dissent and organize movements free of persecution and violent attacks,” she said in a statement.

Almost three-quarters of the known deaths of environmental activists worldwide occurred in Central and South America, according to a report by the organization Global Witness, which analyzed 116 killings in 2014.

Erika Guevara-Rosas, the Americas director at Amnesty International, called the killing of Mr. Baldenegro “a tragic illustration of the many dangers faced by those who dedicate their lives to defend human rights in Latin America, one of the most dangerous regions in the world for activists.”