India, May 21 -- LUCKNOW The investigation into the murder of Chandranath Rath, personal assistant to West Bengal chief minister Suvendu Adhikari, took a dramatic turn after the Central Bureau of Investigation (CBI) gave a clean chit to Ballia resident Raj Singh, 28, whom the West Bengal Police SIT had arrested on May 10.

Singh was released after the CBI found he had been mistakenly detained due to confusion over his name with that of the alleged main shooter Rajkumar Singh. The CBI took over the case investigation after registering a separate FIR in the matter on May 11.

Simultaneously, the CBI tightened its net around the alleged conspiracy by arresting an arms supplier linked to the accused shooters.

Officials said the mistaken arre...