Shajahan VK was arrested by the Delhi Police special cell on July 1 this year after he was deported by Turkish authorities.
Hailing from Kannur in Kerala, Shajahan was allegedly trying to sneak into Syria to join the ISIS when he was held by Turkish agencies and was deported back to India.
"The NIA has taken over the case and started the investigation," a statement from the agency said here today.
"Another accused who had arranged the fake passport for Shahjahan, Mohd Mushtafa alias JP from Mannady, Chennai was also arrested earlier," it said.