The National Investigation Agency (NIA) on Sunday detained three people in connection with the serial blasts in Bodh Gaya last year, but after quizzing them, released two and arrested one, police said.
The three were detained in Arwal district, Superintendent of Police Safiul Haque said.
Mohammad Irfan, a resident of Avgila village, was arrested, while Rajnandan and Ranjan were released after interrogation.
Ten bombs exploded at Bodh Gaya's Mahabodhi temple July 7 last year injuring two Buddhist monks. Three live bombs were later found and defused.