Special judge Sangita Dhingra Sehgal remanded Sanjeev Saxena to police custody till July 21, on the plea by the Delhi police crime branch that his custodial interrogation is required to get to the bottom of the "conspiracy".
Seeking Saxena's custody, prosecution submitted that they have to question him to know the whereabouts of Sanjay, the then driver of Amar Singh with whom he had allegedly gone to the residence of a Bharatiya Janata Party MP to hand over a sum of Rs 1 crore.
The prosecution also submitted that they have to recover the mobile phone used during that period and to ascertain the source of money which allegedly changed hands in the scam.
Slammed by the Supreme Court for a shoddy probe in the cash-for-vote scam, the Delhi police had on Sunday made its first arrest in the case picking up Saxena for allegedly trying to bribe BJP MPs ahead of the United Progressive Alliance government's trust vote in 2008.
Saxena has been booked for various offences under the Prevention of Corruption Act, the police said.