A Brazilian man charged with the murder of mining executive Cecilia Haddad in Sydney has been transferred to Rio’s notorious Benfica jail.
Mario Marcelo Santoro was taken to prison after Rio detectives formally indicted him over the killing of his former girlfriend.
Her fully clothed and weighted body was found in the Lane Cover River on April 29.
Mr Santoro had left Sydney for his native Brazil shortly after her body was discovered.
Rio homicide detectives had questioned Mr Santoro at their divisional headquarters in southern Rio for three days.
Officers say their investigation is ongoing.
Mr Santoro was handcuffed to another prisoner as he was led through waiting reporters to a police van.
Local media reported he was taken to the maximum-security Benfica penitentiary, considered one of Rio’s most violent jails.
In 2004, a prison rebellion triggered by gangs inside Benfica ended with at least 38 prisoners and a prison guard dead.
Many of the prisoners’ bodies were mutilated.
Brazil’s jails are often under the influence of gangs, who run drug trafficking empires from behind prison walls using smuggled mobile phones.
Most are overcrowded, with an estimated 650,000 inmates packed into state prisons built to house fewer than 400,000.
Prosecutors now have 30 days to consider the charges against Mr Santoro while he remains in pre-trial detention.
NSW police are still waiting for formal clearance before travelling to Rio to assist local authorities.