A CBI team on Friday questioned the family members of Raj Singh, accused of murdering Chandranath Rath, the aide of Bengal Chief Minister Suvendu Adhikari, a police officer said.

Superintendent of Police Omvir Singh told PTI that a CBI team arrived in Ballia on Thursday and questioned the brother and mother of the arrested Raj Singh at the police station on Friday.

Raj Singh's sister, Deep Shikha Singh, told PTI that the team seized several documents and CCTV footage of a clothing showroom where her brother worked.

Deep Shikha has demanded security for her brother and added that the family trusts the CBI to carry out its duties impartially.

Raj Singh's mother, Jamwanti, said the family members are fully cooperating with the CBI and that they have also provided CCTV footage of their house.

The team also questioned the showroom's owners and Raj Singh's friends, and others associated with the case.

Meanwhile, Harivansh Singh, advocate of Raj Singh, told reporters that the CBI will solve the case.

Raj Singh, a 25-year-old Ballia resident, was among the three people arrested by the Bengal Police on May 11.

Raj Singh was traced after investigators tracked an online payment made at the Nivedita Setu toll plaza, which led police to the suspects.

On May 13, the CBI took over the case and filed an FIR into Rath's murder. The agency formed a seven-member SIT to probe the incident.

Police suspect that these three were involved in Rath’s killing, though the motive and whether they were hired to carry out the killing are still under investigation.

Rath, the executive assistant to Adhikari, was shot dead in Madhyamgram on May 6, two days after the declaration of the fiercely contested Bengal Assembly results.