RIO DE JANEIRO (Reuters) - He is a symbol of Brazil’s biggest corruption investigation - a ballyhooed battle against impunity for powerful politicians and businessmen.

Jose Dirceu (front R), former Brazilian President Luiz Inacio Lula da Silva's chief of staff, is escorted by federal police officer Newton Ishii as he leaves the Federal Police headquarters to give his testimony in a session of the Parliamentary Committee of Inquiry in Curitiba, Brazil, August 31, 2015. REUTERS/Rodolfo Buhrer

But on Wednesday, federal police agent Newton Ishii sat in the same jail where he had been photographed and shown on TV escorting countless high-profile politicians and executives linked to a kickback scandal at state-run oil company Petrobras PETR4.SA.

It is a long fall for Ishii, perhaps the first Brazilian policeman ever to be exalted in a Carnival song, sung by party-goers who wore masks bearing his likeness and dressed in his black police garb.

Known in Brazil simply as “the Japanese cop,” due to his heritage, Ishii’s face appeared on placards at massive rallies in the past year that demanded the impeachment of now-suspended President Dilma Rousseff.

Ishii’s visit to Brazil’s lower house of congress in February created a commotion as deputies, including the far right-wing Jair Bolsonaro, took selfies with him. Rumors even floated that the agent might consider a political career.

But his growing cult of personality rubbed some high-level federal police officials the wrong way, two authorities familiar with the situation said on condition of anonymity, and Ishii has not been seen in the Petrobras police raids since his congress visit.

Federal police in the southern city of Curitiba, where investigators, prosecutors and a judge are spear-heading the Petrobras probe, said Ishii was arrested on Tuesday afternoon.

His case is under seal, so the exact reason for his detention is not known. But it is likely tied to a previous conviction, the two authorities said.

Ishii, along with several other police, tax collectors and professional criminals, was arrested in 2003 when authorities broke up a ring that bribed authorities to ferry contraband into Brazil over the Triple Frontier area, where Brazil, Argentina and Paraguay meet.

It is a region renowned for trafficking all manner of goods, from drugs and arms to electronics and cigarettes.

Ishii was found guilty in 2009, but had remained free on appeal.

Beyond his corruption conviction, Ishii was accused by the lawyer of a state’s witness in the Petrobras case of selling information about the investigation to the press - which police say they are probing.

Calls to the last known lawyer for Ishii were not returned.

Memes quickly spread online Wednesday - many depicting Ishii, wearing his trademark dark sunglasses and black bullet-resistant vest and sullen expression, escorting a Photoshopped handcuffed version of himself to jail.