"Police should carry out a thorough, effective and independent investigation of this case," executive director Usman Hamid of Amnesty International Indonesia said in a statement on Monday.

"The judicial process must be carried out in a transparent and accountable manner. The victim's family has the right to know what really happened," Usman added.

George was a brother-in-law of Edo Kondologit, a popular Papuan singer and Indonesian Democratic Party of Struggle (PDI-P) politician. 

He died on Aug. 27 after spending less than 24 hours in the custody of the Sorong City Police, who arrested him for questioning in connection with a homicide case involving the robbery and rape of a 70-year-old woman.

Members of George's family said that they discovered two gunshot wounds and other injuries on his body.

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Sorong City Police criminal investigation head Adj. Comr. Misbachul Munir claimed that police "had to shoot" George in the legs because he tried to escape arrest.

Mibachul said that George later died inside a jail cell at the Sorong City Police station after another detainee assaulted him.

"After receiving [medical] treatment, [George] was taken to a jail cell at the Sorong City Police station for questioning. However, another detainee, identified only as C, attacked him inside the cell. He died shortly afterward," Misbachul said on Monday as quoted by kompas.com.

He added that C had confessed to assaulting George. 

Edo and other relatives doubted the police's account. The family held a protest at the Sorong City Police station on Monday, demanding an investigation into George's death in police custody. They also demanded that the police publicly release CCTV security footage from the jail.

Papuan singer and Indonesian Democratic Party of Struggle (PDI-P) politician Edo Kondologit gives a thumbs-up on Oct. 15, 2019 in this file photo. (kompas.com/Andika Aditia)

National Police spokesman Insp. Gen. Argo Yuwono said that the West Papua provincial police had set up a team to investigate George's death.

"The team will investigate if any unlawful procedures were involved during the suspect's [George's] arrest. We will carry out disciplinary action against any officers who are found guilty [sic] of violating [police] procedures," Argo said.

Usman said separately that any policemen found to have committed procedural violations that led to George's death should be taken to court.

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Justice needs to be upheld. The perpetrators should face criminal charges, not just institutional discipline. All this time, policemen and [soldiers] who commit a crime against civilians have rarely been tried [at court]. This indicates the institutions' strong impunity," he said.

Usman added that it was unacceptable that George had been the victim of assault by another detainee while in police custody.

"An investigation must be carried out, because a the safety of detainees is the police's responsibility," he said.