Three FIRs, including one against a company of Delhi Chief Minister Arvind Kejriwal's late brother-in-law, Surender Bansal, were registered on May 8 by the ACB in the alleged scam.
Sharma, who is the founder of Roads Anti-Corruption Organisation (RACO), has also submitted a complaint to the ACB for a probe in the alleged "mysterious" death of Kejriwal's relative.
Sharma was questioned for a couple of hours, sources said.
The ACB team also visited the PWD office to collect some files and documents related to the scam this evening.
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However, Kejriwal has not been named in the FIR.
In the FIR in the alleged PWD scam, three companies have been named-- Renu Constructions, owned by Bansal, Kamal Singh and Pawan Kumar.
In his complaint, Sharma had also alleged that Kejriwal and PWD minister Satyendra Jain had misused their office for grant of contracts to Bansal. However, they haven't been named in the FIR.
RACO, 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.
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 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.
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