Maxciel Pereira dos Santos was shot dead in the town of Tabatinga last Friday, close to where seven Latin American leaders signed a treaty to protect the Amazon.

The murdered activist had worked for the past 12 years to protect indigenous people in the Tabatinga area, close to Brazil’s borders with Peru and Colombia, an association of rights defenders said.

Dos Santos “was murdered in cold blood on a busy avenue at 6:00 pm in front of his family” the association of indigenous protection workers said on its website.

All the indications were he was murdered “because of his fight against illegal practices in the indigenous territory of Vale do Javari,” it said.

The Vale do Javari is home to “the largest number of isolated indigenous people in the world,” and “a permanent target of criminal organizations for illegal exploitation of hunting, fishing, timber and gold.”

Four attacks have been carried out on rights defenders in the area over the past year, it said.