Mumbai's former Police chief Param Bir Singh - who faces at least four cases of extortion in Maharashtra and had been missing since October, leading to rumours he had fled the country - appeared at the city police's Crime Branch Unit 11 office on Thursday morning.
He is currently being questioned at the office.
"I will join the investigation as directed by the court," Mr Singh told reporters at Mumbai airport earlier today, after flying in from Chandigarh, where he had surfaced yesterday.
On Monday, the Supreme Court granted the former Mumbai top cop protection from arrest in a move that raised eyebrows. He was asked to join investigations into extortion charges against him.
Param Bir Singh "does not want to abscond and does not want to run anywhere" but faces a threat to his life, his lawyer told the court, assuring it that Mr Singh was, in fact, in India.
"It should not appear to the court I am afraid. I have full faith in the system. I am ready to appear before a CBI court (but) I am being hounded. I am suffering..." Mr Singh had pleaded.
To that a perplexed court responded: "If the former police commissioner of Mumbai says he faces a threat from Mumbai Police, then what kind of message does it send?"
"The officer shall join investigation. But will not be arrested," the court eventually ruled.
Last week the same court refused to grant Mr Singh any such protection, asking him sternly to first reveal himself. "Where are you? Are you in this country or outside? In some state? Where are you? No protection until we know where you are," the court had said.
Param Bir Singh has not reported to work since May - when he was transferred out as Mumbai Police Commissioner and subsequently accused then Maharashtra Home Minister Anil Deshmukh of corruption; Mr Deshmukh has since been arrested and is now in Enforcement Directorate custody.
Mumbai Police had told the court it had no idea where he was.
On November 17, a Mumbai court said Mr Singh could be declared an "absconder", which means he could be treated as a fugitive from the law.
Earlier this week a notice to that effect was pasted outside his home in the city's Juhu area.
Param Bir Singh was transferred after Mumbai police officer Sachin Waze was arrested in connection with the Mukesh Ambani bomb scare case (an SUV filled with explosives was found near Mr Ambani's home) and the subsequent suspicious death of businessman Mansukh Hiran.
Mr Waze was known to be close to Param Bir Singh and had direct access to him, despite being just an Assistant Police Inspector. Mr Singh was shifted in March - after Sachin Waze's arrest by the NIA.
Inspector Sunil Mane, who was in charge of Mumbai Police's Crime Branch Unit 11 office when Mr Singh was top cop, is now in jail with Sachin Waze.
After his transfer (to the Home Guard), Mr Singh made sensational accusations against Mr Deshmukh, accusing him of asking police officers to collect bribes from hotel and bar owners.
Mr Deshmukh has denied all these allegations.
With input from PTI