Ten people, including women and children, died after miscreants set fire to houses in Bogtui village on March 21.
Ritan Shiekh was nabbed from his house in Bogtui in the early hours, an official said.
"This man's name cropped up every time we spoke with eye-witnesses. Today, he was giving us different versions & trying to confuse us. We arrested him, will continue questioning him," official said.
The CBI visited Rampurhat police station during the day, and collected the case diary and documents linked to Bhadhu Shiekh's murder investigation.
Birbhum killings direct fallout of Trinamool leader's murder, carried out in organised manner: CBI report
The Central Bureau of Investigation's findings said that the rivalry was 'long-standing' between two groups -- one of Bhadu Sheikh and another of Palash Sheikh and Sona Sheikh.
The bench, also comprising Justice R Bharadwaj, ordered the transfer of the murder case of Sheikh from the state police to the CBI for the purpose of a complete investigation.
The CBI arrested the four persons -- Bappa, Shabu, Taj Mohammad and Serajul -- from Mumbai where they fled to following the massacre in Rampurhat's Bogtui village on March 21.
The four accused had fled from Bogtui to the Maharashtra capital soon after the killings, and they were apprehended from their hideout early on Thursday morning.
The CBI, which is probing the Bogtui violence on the direction of the HC, submitted that it has no probing Bhadu Sheikh's murder too if the court so ordered.
A division bench presided by Chief Justrice Prakash Srivastava had asked CBI about its stand on it while hearing a prayer for an order to direct the state police to hand over the probe.
At least 10 FIRs have been filed and over 20 arrested in Bhadu Sheikh's murder case so far.
During the assessments, one psychologist will be present to note their body language as well as facing expressions, which will be treated as evidence.
Charred bodies of the eight people were recovered from Bogtui village in Rampurhat police station area of the district, hours after the murder of a local TMC leader.
Last week, eight people were burnt alive, while another succumbed to her injuries later, in Bogtui village near Rampurhat town of the district in the suspected fallout of a TMC activists's murder.
The Central Bureau of Investigation (CBI), which is investigating the killings following a Calcutta High Court order, is yet to make any arrest.