"I think of him every day," his widow, Alessandra Sampaio, told AFP of her husband, who was shot dead in the Amazon on June 5, 2022 along with Indigenous-rights activist Bruno Pereira.

She was in London for the global launch of "How to Save the Amazon", which Phillips, a freelancer for The Guardian and the Washington Post, was researching when he was killed.

The double murders triggered an international outcry and drew attention to the lawlessness fuelling the destruction of the world's biggest rainforest.

Brazilian federal police have concluded the men were killed because of Pereira's monitoring of poaching and other illegal activities in a remote reach of the Amazon.

Three years to the day after the murders, a prosecutor from Amazonas state indicted the suspected mastermind, the state prosecutor's office said in a statement Thursday. So far, several suspects have been charged in the killings.

Phillips, who had taken a break from journalism to write his book, was seeking to raise the alarm about the environmental damage and illegal activities plaguing the region.

"He died trying to show the world the importance of the Amazon," said Sampaio.

Pereira was a former senior official with Brazil's Indigenous affairs agency, and disappeared along with Phillips as they travelled through a remote Indigenous reserve, close to the borders of Colombia and Peru.

Their hacked-up bodies were found and identified days later, after an alleged accomplice confessed to burying them.

Phillips, 57, was shot in the chest, while Pereira, 41, sustained three gunshot wounds, one of them to the head.

They were killed in the northwestern Javari Valley, where drug traffickers, illegal fishermen and hunters, and gold miners operate.

"It was his second-to-last trip. One more was left, and he would have finished the book," said Sampaio, adding Phillips had already written the first four chapters.

- 'Dom's book' -

After his death, his widow spent months collecting his extensive writings, journals and reams of notes.

"He had two or three notebooks from each trip, with dates, places, explaining everything," she said. But she confessed that at times she had to stop as she got "too emotional".

Each new chapter has been written by a group of six journalists and writers: Britons Jonathan Watts and Tom Phillips; Americans Andrew Fishman, Stuart Grudgings, and Jon Lee Anderson; and Brazilian Eliane Brum.

The book is "dedicated to everyone fighting to protect the rainforest".

They all travelled to the region, and interviewed new people following Phillips's trail in a bid to faithfully complete his manuscript.

The afterword has been written by Beto Marubo, a leader of the Indigenous Marubo people, with Amazonian activist and writer Helena Palmquist.

Sampaio, who lives in Brazil's northeastern Salvador da Bahia region, paid tribute to the "loyal friends" who helped complete the book, which she says is also a tribute to activist Pereira.

"There's no way to separate Dom and Bruno. They're there together. It's a message for everyone to understand the importance of the Amazon and its people," she said.

Watts, global environment writer with The Guardian, said: "It's more than a tribute to Dom, it is Dom's book."

"In this process, I'm always imagining what would Dom think, but it's my imagination," he added.

"I'm sad that Dom is not here to see it, but I'm very happy that we are here."

The murders threw a spotlight on a long-threatened corner of the planet, and stoked criticism of the policies of Brazil's former president Jair Bolsonaro, accused of encouraging the plundering of the rainforest.

The book, launched simultaneously in Britain, Brazil and the United States, ends with a plea from Marubo for more people like Phillips and Pereira, who he says wanted to "truly help" save the Amazon.

"They were brave and they acted. If everyone did the same we might begin to see change," Marubo writes.