Yesterday, six PWD officials were quizzed, while the anti-graft body has called more officials tomorrow for questioning.
They will be probed on the process followed to clear the bills and whether there was pressure on them to clear the bills.
The FIRs have been registered on the basis of a complaint filed by founder of Roads Anti-Corruption Organisation (RACO) Rahul Sharma alleging irregularities in the grant of contracts for roads and sewer lines in Delhi in 2015-16.
Sharma also gave a complaint yesterday alleging that he has been getting threats since he filed the complaint.
"Three cases have been registered on a complaint by RACO. Since there are three separate companies, three separate FIRs under the sections of forgery, cheating and Prevention of Corruption Act have been registered," ACB chief Mukesh Kumar Meena had said.
In the FIR registered last week, three companies have been named-- Renu Constructions, owned by late Bansal, Kamal Singh and Pawan Kumar.
The ACB had also conducted raids at the PWD office last week and collected some files.
The ACB had also examined the complainant.
The probe has come in the backdrop of graft allegations made by axed Delhi minister Kapil Mishra against Kejriwal. RACO (Roads Anti-Corruption Organisation), an organisation which claims to monitor construction projects in the national capital, had alleged that a firm linked to Bansal was involved in financial irregularities in building a drainage system in north-west Delhi.
It had alleged that the bills sent to the PWD for the works, which were not completed, were "false and fabricated".
Sharma had alleged that M/s Renu Construction Company, operated by Bansal, was awarded the contract to build a drainage in north-west Delhi's Bakoli village in April 2015.
"It had, in 2015-16, obtained a contract for the works which were never completed, while the payments were cleared. Even the bid and its technical marks were manipulated," the complaint, dated January 9, had alleged.
The invoices (purportedly obtained through an RTI application by RACO from the PWD) pertaining to the project were sent to the Sales Tax department for verification.
The department had informed in writing that the bills sent to the PWD were false and fabricated, Sharma had alleged.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)