Subhani Haja, the accused in the IS joining case was found guilty by a Special Court of the National Investigation Agency (NIA) here on Friday.
The court will pronounce the punishment on September 28.
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Haja was said to be one of the few Indians who returned to the country after joining the proscribed organisation.
Convicting Haja in the case, P. Krishnakumar, the NIA Special Judge, observed that he had committed offences under Sections 125 of the Indian Penal Code for waging war against an Asiatic country and Criminal conspiracy under Section 120 b of the Indian Penal Code.
The court found him punishable under various sections of the Unlawful Activities (Prevention) Act.
The NIA had invoked Section 125 of the Indian Penal Code, a rarely invoked section which deals with waging war against an Asiatic country, against the accused in the case.
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Haja was arrested by the agency on October 5, 2016.
The NIA had argued that the accused, who joined the ISIS between April and September 2015, had waged war against the government of Iraq. He was trained by ISIS in Mosul in Iraq in combat and warfare and was deployed in the war front of Iraq.
