The NIA on Tuesday released pictures of five suspects in the serial blasts at Mahabodhi temple premises.
According to reports, three of the four suspects belong to India, while one is a foreigner.
Struggling to find a breakthrough in the Bodh Gaya blasts probe, NIA had earlier this month released the sketch of a person who was seen moving in suspicious manner before the blasts.
Two monks were injured in ten blasts that took place early in the morning of July 7 in Bodh Gaya. Three unexploded bombs were found.
The temple and the Bodhi Tree, under which Lord Buddha is believed to have attained enlightenment, did not suffer any damage in the blasts which shook the holy town frequented by Buddhist pilgrims from Sri Lanka, Myanmar, China, Japan and the whole of south east Asia.