Federal police said in a statement they also seized ammunition and a belt, but did not say why the items were seized, who owned them or where they were found.
De Oliveira told The Associated Press on Friday that he had visited Pelado in prison and that local police had tortured Pelado on his own boat, which was also seized by authorities.
Federal police did not immediately respond to an AP request asking why Oseney da Costa de Oliveira was mentioned in her statement, which is not standard police procedure.
Indigenous people who were with expert Bruno Pereira and British journalist Dom Phillips have said Pelado waved a rifle at them the day before the two men disappeared.
He denies doing anything wrong and claims police tortured him to try to get a confession, his family told the AP.
The search for the missing men continued on Tuesday after a backpack, laptop and other personal belongings were submerged in a river on Sunday.
Pereira, 41, and Phillips, 57, were last seen on June 5 at the entrance to the indigenous area of the Javari Valley, which borders Peru and Colombia.
Federal police released a statement Monday denying media reports that the bodies of the two men had been found.
Search teams are focusing their efforts on a spot on the Itaquai River, near the town of Atalaia do Norte, where volunteers from the Matis indigenous group on Saturday found a sail from the boat used by the missing men.
The Javari Valley has seven known indigenous groups – with some only recently contacted, such as the Matis. The valley also has at least 11 uncontacted groups, making the region the largest concentration of isolated tribes in the world.
There have been violent clashes between fishermen, poachers and government officials in that area. Violence has increased as drug gangs compete for control of the waterways to transport cocaine, although the Itaquai River is not a known drug route.