The first accused arrested in connection with the scam was Singh's close aide, Sanjiv Saxena who directly charged Amar for providing him money in order to bribe the the MPs in 2008.
The Union Home Ministry is also believed to have granted permission to the Delhi Police to question Amar Singh.
Saxena was allegedly caught on camera offering one crore if the MPs agreed to vote in favour of the UPA during a no-confidence vote moved against Prime Minister Manmohan Singh in July 2008. Singh was then a senior leader of the Samajwadi Party, which was an ally of the UPA.
Allegations were levelled by former BJP MPs Ashok Argal, Faggan Singh Kulaste and Mahavir Bhagora that Saxena delivered Rs one crore to them at the residence of Ashok Argal to vote in favour of UPA.
On the other hand, Suhail Hindustani in his statement indirectly charged Singh by claiming that the ex Samajwadi leader was acting and working on Prime Minister's direction.