The Calcutta High Court had in August handed over probe to the CBI.
The CBI, which is probing cases of post-poll violence in Bengal, has arrested Ravi Baske, a local TMC leader in Birbhum district, in connection with its investigation into the murder of BJP worker Gaurav Sarkar, sources in the agency said on Tuesday.
Sazlul Rahman, the TMC's Illambazar block president, has confirmed that Baske is a member of the state's ruling party and that he has been apprehended.
According to Siddhartha Chatterjee, Baske's lawyer, the TMC leader was on Tuesday produced before Bolpur court, which sent him to CBI custody for three days.
He was apprehended from Illambazar area on Monday night.
Earlier, in September, another TMC leader, Dilip Mirdha, was arrested from Hooghly for his alleged involvement in the case.
Sarkar was killed on May 2, following the declaration of assembly poll results.
The Calcutta High Court had in August handed over probe into "heinous" cases of post-poll violence, involving rape and murder, to the CBI.
The BJP has alleged that many of its workers were attacked and killed by members of the ruling TMC in the aftermath of the state elections.