The Central Bureau of Investigation arrested Karti Chidambaram on Wednesday after Indrani Mukerjea – who is jailed in the Sheena Bora murder case and is also an accused in the INX Media case – alleged that then Finance Minister P Chidambaram had asked her and her husband Peter Mukerjea to help his son’s business.

In a statement to the CBI, Indrani Mukerjea alleged that the Mukerjeas and Karti Chidambaram had struck a $1-million (Rs 6.5-crore) deal to get the Foreign Investment Promotion Board’s approval for Foreign Direct Investment in INX Media in 2007, The Indian Express reported.

INX Media has given investigative agencies four invoices, supposedly countersigned by the company’s former director Peter Mukerjea, that purportedly show payments amounting to more than $700,000 (approximately Rs 4. crore) to firms linked to Karti Chidambaram, The Hindu reported. The agencies are now verifying the authenticity of the documents.

The CBI and the Enforcement Directorate said Indrani and Peter Mukerjea had told them that they met P Chidambaram in his North Block office in connection with the foreign investment board’s approval for FDI in INX Media. The agencies alleged that the former finance minister had asked the Mukerjeas to “help the business of his son Karti, and to make foreign remittances for this purpose”.

The Mukerjeas also said they met Karti Chidambaram in Hotel Hyatt in Delhi, where the $1 million-deal was made, the CBI and ED claimed, according to The Indian Express.

Delhi’s Patiala House Court on Wednesday gave the CBI one-day custody of Karti Chidambaram to interrogate him in the INX Media case. Senior advocate and Congress leader Abhishek Manu Singhvi represented him.

The CBI filed a First Information Report in the INX Media case on May 15, 2016, alleging there were irregularities in the Foreign Investment Promotion Board’s Foreign Direct Investment clearance to the company in 2007, when P Chidambaram was the finance minister. The agency accused Karti Chidambaram of using his father’s influence to get the FDI approval. It also alleged that INX Media had bribed Karti Chidambaram to scuttle a tax investigation.