The Central Bureau of Investigation is looking into India’s largest law firm after they seized documents related to the Punjab National Bank scam at their office in Mumbai, Reuters reported on Wednesday. A lawyer representing the government and an unidentified police official told the news agency that the documents were found at the office of Cyril Amarchand Mangaldas mid-February.

Billionaire diamond jeweller Nirav Modi, the main accused in the scam, sent cartons of documents to the law firm’s office after the Rs 13,500-crore fraud came to light. K Raghavacharyulu, one of the prosecutors in the case, and two unidentified CBI officials said the law firm had these documents in possession even though it was not representing the jeweller or his companies.

“CAM was not their attorney in the PNB fraud case, 100% sure...that is why they could not cite attorney-client privilege,” Raghavacharyulu told Reuters. He said his assessment was based on regular briefings from CBI officers.

Raghavacharyulu said the investigating agency’s first chargesheet against Modi and others, which was filed in May, mentioned that “incriminating documents/articles relevant to the case” were found the law firm’s office. However, Cyril Amarchand Mangaldas was neither charged nor was it named as witness in the case.

But an unidentified CBI official said the police had summoned, questioned and recorded the statement of at least one junior lawyer from the firm before the chargesheet was filed. The agency is reportedly still undecided about charging the law firm for allegedly concealing evidence or naming it as prosecution witness, and therefore has not produced the statement in court, the official added.

The law firm refused to comment on the matter. “[CAM] strictly follows the legal best practices and does not comment on matters that are sub judice or are under investigation,” the company’s spokesperson Madhumita Paul told Reuters. The company said the news agency’s findings were “full of false and speculative statements”.