According to the first investigation results, the suspected murderers of a British journalist and an indigenous expert in the Brazilian Amazon probably acted alone.
"The investigations indicate that the perpetrators acted alone and that no client or criminal organization was behind the crime," the federal police said on Friday.
Two suspects have been arrested following the disappearance of Dom Phillips and Bruno Pereira in the Javari Valley on the border with Peru and Colombia.
One admitted that he was involved in the murder of the two men and led the police to human remains.
They were taken to the capital, Brasília, for identification.
The results are expected within ten days.
Phillips researched a book about the protection of the Amazon, the strong economic interests in its exploitation and various development models.
The motive for the alleged murder was initially unclear.
Among other things, the investigators check whether the crime is related to illegal fishing or drug trafficking.