Details and documents related to the probe have been handed over to an NIA team, which arrived here from Delhi yesterday, a state government official said.
The agency, which takes over the probe from Madhya Pradesh Police, is now expected to start questioning the three accused -- Mohammad Danish, Mohammad Atif Muzaffar and Sayed Meer Husain -- who were arrested from Hoshangabad district of Madhya Pradesh, hours after the blast, the official added.
The three arrested persons, said to be influenced by the ISIS ideology, have been accused of planting a pipe bomb in the train.
According to the police, examination of the remnants of the pipe bomb had revealed that "ISIS now in India" was written over it.
At least 10 people were injured, three of them seriously, in the IED blast on the train near Jabri station in Shajapur district of Madhya Pradesh on March 7.