Search teams in Brazil have discovered "apparently human" remains in the river where the missing British journalist and Brazilian indigenous expert were last seen in the Amazon rainforest.

Aljazeera News reported that police said it may be the biggest break yet in the five-day investigation on the disappearance of the two men.

Federal police noted that "organic material" is being sent for forensic analysis along with blood found on a suspect's boat that will be compared with genetic material from journalist Dom Phillips and Indigenous expert Bruno Pereira.

Police noted that the investigation into the disappearance of the two men had led to the arrest of one man.

The suspect was caught in possession of drugs, a shotgun and ammunition restricted for military use. However, the suspect was not named, as reported by The Guardian.

Police sources said they had detained a man named Amarildo da Costa de Oliviera earlier in the day on similar charges. However, the Amazonas state police chief told reporters it was too early to connect any suspect directly to the pair's disappearance.

Carlos Alberto Mansur said that they have material that makes them suspect there is a link to the fact, but it is still "just a suspicion," and is still being investigated. Mansur said that they still do not have a strong indication that a crime was committed.

Da Costa has a nickname known as Pelado and was reported to have threatened Philips and Pereira and a group of 13 Indigenous people on Saturday morning.

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Missing Men in Brazil

Police said that the genetic material collected will be used in comparative analysis with the blood found on the boat.

Phillips was in the Amazon reporting for a book on sustainable development and was accompanied by Pereira, who is an explorer and Indigenous advocate who had years of experience in navigating the rivers and forest.

Another The Guardian report noted that Pereira had been threatened before for his work in the area, helping indigenous communities protect their traditional lands from invaders.

State Judge Jacinta Silva dos Santos said that the proceedings are under seal and she could not comment on whether other audiences are planned for the fisherman Pelado.

Da Costa was one of the last people to see Phillips and Pereira on Sunday.

State police detectives said their focus is on poachers and illegal fishermen in the area.

Probe on Amazon Disappearance

Paulo Marubo, the president of a Javari Valley association of Indigenous people, Univaja, said that Phillips and Pereira had been threatened by the men brandishing guns.

Marubo said that the British journalist photographed the men at the time, including local resident da Costa.

Phillips and Pereira went to a nearby federal base that has the permanent presence of Brazil's bureau office for Indigenous affairs, known as FUNAI.

Raimundo Mayoruna said that they went there but did nothing, adding that officers did not go after Pelado at all, according to a Washington Post report.

FUNAI and the National Guard has yet to comment on the matter.

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This article is owned by Latin Post.

Written by: Mary Webber

WATCH: Dom Phillips and Bruno Pereira filmed on Amazon expedition in 2018 - from Guardian News