Police investigating the murder of the British journalist Dom Phillips and indigenous advocate Bruno Pereira have identified five more people connected with the killings, bringing to eight the number of suspects in a crime that has shocked Brazil. Police had already arrested two brothers, one of whom confessed to the crime, and a third man handed himself in to authorities on Saturday. State police in Atalaia do Norte – the riverside town where Phillips and Pereira began their final journey – told the Guardian the five suspects were being investigated over their alleged involvement in assisting the men in moving the remains of Phillips and Pereira 24 hours after the shooting. Investigator David Da Rocha described the investigation as “90% complete”, saying that the expected arrests were likely to be the last in the process. He said the five men he expected to arrest were relatives of the two brothers in custody. Police were waiting on a court order to initiate the apprehensions and hoped to also charge them each with homicide. Da Rocha maintained his belief that the murder suspects had not acted on anyone’s orders and stated the crime was not part of a broader criminal conspiracy. This characterisation, shared by Brazil’s federal police, has been forcefully opposed by Indigenous activists in the region, who have argued that the killings were linked to organized crime groups. Phillips was a British journalist who was researching a book on sustainable development in the Amazon region and Pereira was helping him negotiate remote parts of the rainforest where he was carrying out interviews. The pair were shot dead on 5 June and buried deep in the rainforest. Their bodies were discovered last week, when one of the two brothers confessed to the crime. Police said Phillips had been killed with one gunshot to the body, while Pereira had been shot three times, twice in the chest and abdomen region and once in the head. The weapons used in the killing were of the type used by hunters, police said. The announcement came as unions working at Brazil’s national indigenous agency, Funai, called a five-day strike for this week aimed at ousting the president of the organisation, who they say is working against the interest of Brazil’s Indigenous people. Officials with three unions are to vote on the strike on Monday, but are confident that members in the majority of Brazil’s 27 states will join the stoppage, which is also intended to force authorities to broaden the investigation into the crime. “The focus of the strike is to force out [the Funai president] Marcelo Xavier,” said Priscila Colotetti, the executive director of Indigenistas Associados, an association of Funai employees. “Under Xavier, it’s not that the Indigenous policies are hard to enact, it’s that there are no Indigenous policies. So we need a longer strike to put the pressure on. “We are also pushing for a proper investigation into the killing of Dom and Bruno so they find out who ordered the crime.” Officials claimed last week the suspects had acted alone, but that conclusion was questioned, not least by local Indigenous groups, who had previously reported the presence of drug gangs and organised crime mafias in the region. The announcement added to the widespread lack of confidence local people put in state organs such as the police and, increasingly, Funai. The Indigenous foundation has been undermined and underfunded by Brazil’s far-right president, Jair Bolsonaro, current and former officials there said. Bolsonaro wants to open up Indigenous land to loggers and miners, further threatening the communities who have lived in the area for thousands of years. Xavier’s place at the head of an organisation charged with the care and protection of an estimated 235 Indigenous tribes has also been questioned, including by Pereira, a former Funai employee. Xavier said that in the days after the pair went missing, they had not secured the necessary permits for entering Indigenous land, as required in Brazil. However, Indigenous groups said they did not need the permits because they had not ventured on to Indigenous territory. A judge agreed, and told Xavier to remove his statement from the Funai website and refrain from denigrating the two missing men. Funai complied. Funai made a belated statement on 16 June, saying: “Pereira leaves an immense legacy” and celebrated what it called his “extreme dedication … to Indigenous people, for whom he worked tirelessly”. Pereira, 41, had already clashed with Xavier, a former police chief appointed by Bolsonaro in July 2019. Pereira worked with Funai until late that year, when Xavier removed him from his post. Pereira said he believed the decision had been taken because he had led a successful operation against illegal mines on Indigenous land. After leaving Funai, the father of three went to work with Indigenous communities in the Javari Valley, a remote and densely forested region along Brazil’s western border with Peru. It was there, on a quiet stretch of the Itaquaí river, that he and Phillips were last seen alive. Sunday’s strike call comes five days after union members at Funai’s headquarters in the capital, Brasília, were joined by colleagues in two other states in a lightning one-day stoppage. Colotetti said staff were being threatened with dismissal if they went ahead with the strike, but would not be intimidated. “We will lose the money from the days we are out and there are other threats as well, coming through back channels,” she said. “People in senior positions are being warned they will be removed, and those here on secondment are being warned they will be sent back. The directors are trying to put a brake on it.”