"The arrested person has been identified as Farooq Mollah of Panchyat Samiti of CPI(M)," the Mumbai police department said in a release.
"The West Bengal police, after the incident, had put his (Mollah's) phone numbers under surveillance and one of his numbers was traced to Malvani. Once his presence was confirmed, the WB police contacted us and a trap was laid, following which Mollah was nabbed," the release said.
Mollah was produced before a local court which granted his transit remand to West Bengal.
Four TMC workers were hacked to death at Khanri near Raidighi police station on June 14 night while they were returning from a party meeting. Three more TMC workers were injured in a bomb attack and were admitted to Diamond Harbour district hospital.
Five CPI(M) activists, including the party's Zonal Secretary Bimal Bhandari were arrested on June 17, a day after the ruling Trinamool Congress had lodged an FIR against 21 Marxists, including former minister Kanti Ganguly.