Over 30 Maoists came to the village, about 90 km from Koraput, on Sunday night and asked Ghasi Kendruka (35), a sikshyasahayak attached with a school, to come out of his house.
They the took him to a nearby mango orchard and slit his throat, the police said.
The rebels, who branded Kendruka a police informer and shouted slogans, left posters and letters claiming responsibility for the killing, they added.