Although the government has not found any terrorist involvement in the unsuccessful May 25, 2011 bomb blast outside Delhi High Court, investigators have found evidence that links Indian Mujahideen's mastermind Yasin Bhatkal with the dud explosive.
The case is being investigated by the National Investigating Agency.
Top sources said the needle of suspicion points at Yasin as the chemical impurities found in the ammonium nitrate fuel oil explosive outside the high court match the impurities found by investigating agencies in ammonium nitrate seized from the Meer Vihar, Mundka factory of Mohammed Irshad on December 1, 2011.
Yasin used to work at this factory of his father-in-law Irshad before he gave the police the slip at Tambaram in Chennai on November 26, 2011. Irshad, a resident of Samastipur in Bihar, was arrested the same day.
Lead investigators are still scouring the country for Yasin Bhatkal and two other IM cadres, Waqqas and Tabrez, accused in the 13/7 Mumbai blasts and the August 1, 2012 Pune blasts, for conclusive proof.
Senior officials said that while Irshad has no clue about the May 25, 2011 blast, IM terrorist Qateel Siddiqui, part of the Darbhanga module, had told his interrogators that Yasin Bhatkal smiled when he asked him about the explosive.
Siddiqui, who was arrested by Delhi Police in November 2011, was murdered in Pune jail on June 9, 2012.
The May 25, 2011 incident was a narrow miss as the detonators failed to trigger the improvised explosive device. The court was again targeted on September 7, 2011. Eleven people lost their lives in the second blast.