A team led by CID special superintendent Bharati Ghosh last night arrested Chandi Karan, CPI(M)'s Belatikri local committee secretary.
With this, 19 of the 20 accused in the case have been arrested.
Another CPI(M) leader Fullara Mandal is still absconding.
The main accused Anuj Pandey, CPI(M)'s former Binpur zonal committee secretary, was arrested from Chandrapura in Bokaro district on May 6 last.
Five more accused in the case, all local CPI(M) leaders, were arrested from Hyderabad on April 30 last.
Nine persons were killed in indiscriminate firing allegedly from CPI(M) leader Rathin Dandapat's house at Netai village on January 7, 2011.
The Calcutta High Court had ordered a CBI inquiry into the massacre in February 2011, expressing dissatisfaction with a CID probe then. The then Left Front government's appeal against the order was turned down by the Supreme Court.