The CBI on Tuesday questioned the officer on special duty to Rajasthan chief minister Ashok Gehlot in connection with the alleged suicide of a police officer in May, at a time the Congress government is facing a threat to its survival because of a rebellion linked to the BJP.

The questioning of the OSD came two days after Rajasthan police registered a case against senior BJP leader and Union minister Gajendra Singh Shekhawat and summoned him for questioning, accusing him of conspiring to topple the Rajasthan government.

Audiotapes containing purported horse-trading conversations between Shekhawat and a Congress rebel are being cited as evidence. The central water resources minister and Jodhpur MP has denied that the voice in the tapes is his.

Last week, the income tax department and the Enforcement Directorate had conducted raids at the premises of two persons said to be close aides of Gehlot. The raids had come a day after Gehlot had accused the BJP of trying to overthrow his government by offering Rs 15 crore each to MLAs.

Sources on Tuesday said that the OSD to Gehlot, Deva Ram Saini, was called to the CBI’s office in Jaipur. “OSD Saini was questioned by a team from the special crime unit of the agency from Delhi in connection with the death of Rajgarh station house officer Vishnudutt Vishnoi. His statement was recorded as part of the investigation into the police officer’s death,” a CBI officer said.

The CBI had questioned Congress MLA Krishna Poonia on Monday for three hours in connection with the case. Poonia, who represented India at the Olympics before joining the Congress, is among the party MLAs who are being kept at a hotel in Jaipur to thwart poaching attempts.

Vishnoi, the station house officer at Rajgarh in Churu district, was found hanging from the ceiling of his residence in May. Two purported suicide notes had been recovered — one addressed to Vishnoi’s parents and the other to the superintendent of police of the district.

In the purported suicide notes, Vishnoi had said he was not being able to bear the pressure being put on him and added that he had tried to give his best to Rajasthan police.

The BJP had accused Poonia, the MLA of Churu’s Sadulpur, of pressuring the SHO. Poonia has denied the allegations.

Vishnoi’s brother had filed a police complaint alleging that the officer had been under pressure, which prompted him to commit suicide.

Acting on the complaint, the Rajasthan government had handed over the probe to the CBI last month. The CBI has lodged an abetment of suicide case against unknown persons.

Rajasthan had in 1990 communicated to the Centre its denial of “general consent” to the CBI to carry out any investigation in the state.

On Monday the Rajasthan government had issued a notification iterating this position. The notification said prior approval would have to be taken from the state government on a case-by-case basis to probe any crime falling under Section 3 of the Delhi Special Police Establishment Act, by which the CBI is governed.