The attack came hours before US Secretary of State Mike Pompeo was to meet with negotiators from the Afghan government and the Taliban in the Qatari capital Doha.
Prosecutors in Graz said over 70 people are under investigation in the new case and 60 properties, including apartments and offices, were searched.
The person is Muhammad Polakkani, 27, a native of Mankavu, who was deported from Georgia in September this year.
Kotey and Elsheikh were involved in abducting American, European and Japanese hostages in Syria from 2012 to 2015 along with two other British members of the "Beatles."
The woman followed her first husband to Syria in 2015 and lived in the Islamic State stronghold of Raqqa with their three children, according to the court.
NIA officials, including A P Shoukat Ali who investigated the case against Subahani, were hosted by French agencies to share information about the November 2015 Paris attack.
In 2015, Subahani reached Iraq via Turkey and joined IS. He was trained and deployed at the war front in Mosul. He later decided to return after seeing his colleague die in the war.
The community’s numbers have been declining for years because of deep-rooted discrimination in the majority Muslim country.
The NIA judge P Krishnakumar’s judgment, which runs to 122 pages and 210 paragraphs, discussed 14 points to conclude why the accused was found guilty. The court will announce the sentence on Monday.
On Friday, NIA filed a petition requesting the court to issue a direction restraining the media from publishing the identity of the IFS officer.
Filing the charge sheet in a Special NIA Court in Delhi, the agency named a Kashmiri couple — Jahanzaib Sami, 36, and Hina Bashir Beigh, 39.
The Islamic State group, which once controlled large swathes of Iraq and Syria, lost its last Syrian strongholds in early 2019.
The suspect had scouted Istanbul's main Taksim Square and surrounding areas with the aim of carrying out a "sensational" attack
Western Syria has historically been controlled by Russian-backed Syrian government troops, while the US and its allies, the Syrian Democratic Forces, have largely been in the north and east.
Though Indian intelligence agencies were able to corroborate details on the death of a few Malayalis, they could not specifically confirm each death reported so far.