A fourth suspect has been arrested following the violent death of British journalist Dom Phillips while investigating in Brazil. The man, whose first name was Colombia, “spontaneously” turned himself in, the Brazilian police said on Friday.

He wanted to refute allegations circulating in the press that he had ordered the murder of Phillips and the indigenous expert Bruno Pereira.

The police also said that “Colombia” said they knew one of the men arrested in connection with the murder because he bought fish from him. However, since “Colombia” presented the investigators with forged identity papers, he was also arrested.

Phillips, 57, and Pereira, 41, went missing on June 5 while on an expedition to a remote part of the Amazon. Ten days later, a suspect led police to where he had buried their bodies.

Human remains unearthed at the site have been positively assigned to the two missing persons. Both men had been shot.

Phillips, who regularly writes for the British “Guardian” as a freelance journalist, and the Brazilian indigenous expert Pereira had been researching a book in the Javari Valley on violence against indigenous people and sustainable protection of the rainforest. Gold miners, poachers and drug gangs are active in the region, which borders Peru and Colombia.

Police believe Phillips and Pereira’s murders may be related to illegal fishing in the Amazon. Now it is being investigated whether “Colombia” was involved in illegal fishing or financed it, said the chief of the federal police in the state of Amazonas, Eduardo Fontes, at a press conference on Friday. However, the suspect rejects any involvement in the double murder.