Irishman Patrick Hickey, 71, was arrested in a dawn raid at the Hotel Windsor Marapendi in his bathrobe on Wednesday for alleged ties to an illegal price-gouging scheme for tickets to the Olympics.
Now, he is sharing a prison cell with Kevin Mallon, a director of THG, the international sports hospitality company caught up in the investigation, say prison authorities.
Rio's Bangu prison complex, which has more than a dozen separate units in the city's rough western reaches, is notorious for violence and uprisings.
The G1 news website reported last year that inmates in the Bangu 10 part of the complex where Hickey is being held were eating damp toilet paper to kill their hunger.
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However, it is likely that Hickey, like other high-profile prisoners held in Bangu, is in one of the safer areas separated from the general prison population. Those units do not have the extreme overcrowding and violence of the others but are bleak nonetheless.
Officials for Rio state penitentiaries said Hickey was getting the same treatment as any other inmate, including the right to a daily walk outside and scheduled visits.
He was admitted to Samaritano hospital for chest pains after his arrest but released the next day into police custody.
IOC President Thomas Bach said there was no disciplinary investigation into Hickey and urged the public to avoid rushing to judgement.
"What we know is that he has not been heard by a judge yet and, more so, the presumption of innocence prevails," Bach told a news conference during the closing weekend of the Rio Games.
"We respect the laws and legal procedures here in Brazil and cannot comment further on this," he said. "I cannot comment on the case because it is a legal procedure and we do not have information."
Hickey temporarily stepped aside as an IOC executive board member, head of the European Olympic Committee and the Olympic Council of Ireland after his arrest. He had an appeal for bail denied by a Brazilian judge.
Bach said there would be no disciplinary commission to investigate Hickey because the Irishman had temporarily stepped down from his IOC responsibilities.
The IOC's ethics commission "is actually in contact with the authorities in Brazil. At this time there is no reason for any action, given that Mr Hickey has suspended himself from any (IOC) activities," said Bach, who has headed the IOC since 2013.
"It took note of this self-suspension and will follow up the case according to the developments."
Hickey was part of the IOC's powerful board and a longtime IOC member but Bach offered little in terms of specific support for a once high-profile colleague, who sat right behind him at the Aug. 5 opening Games ceremony.
The Irishman is still listed as an IOC member on the website of the organisation but with two asterisks next to his name denoting self-suspension.
Asked about support for Hickey from the IOC, Bach merely repeated that he should be presumed innocent.
(Additional reporting by Brad Brooks; Editing by Clare Fallon)
