Following a tip-off, the four were arrested from forest areas near Rajalkonda and Elkanur villages under the Kalimela police station jurisdiction, Malkangiri Superintendent of Police Jagmohan Meena said.
The four were involved in the killing of Dambaru Nayak at Kurup village on the night of October 6 on the suspicion of being a police informer, he said adding, more arrests are likely to be made in connection with the murder soon.
The arrested naxals, active in Maoist activities for the last several years, have admitted their involvement in the murder, police said.
The body of Nayak with injury marks was later recovered from a forest area on the outskirts of the village, police said adding, his head was hit with stone and some blunt object.
A hand-written note left behind at the site by the assailants stated that Nayak was eliminated as he worked as an informer for the police in the area, they said.