Superintendent of Police Rajiv Ranjan said that Ekka was arrested from his Simdega residence on Thursday and sent to judicial custody by a local court.
Ekka is accused of conniving with an extremist group for eliminating a para-teacher, whose body was found at Kolibera of the district on Thursday.
After the family of the para-teacher filed a complaint, Ekka was charged with various IPC sections, including 302 (murder) and 120B (criminal conspiracy), according to police sources.
A sitting MLA and out on bail in connection with corruption charges, Ekka is contesting from Kolibera constituency.
His wife, Menon Ekka, is contesting from Simdega from the same party.