Banned Indian Mujahideen terror outfit is suspected to be behind the low intensity blast outside the Delhi high court in May last year.
The National Investigation Agency, which took over the probe in December last year after the Special Cell of Delhi police failed to make any headway, has got some leads to suggest that the blast on May 25 last year was a handiwork of the banned terror outfit, official sources said.
The investigations into this blast had virtually slipped into the background after the high court premises were rocked on September seven by an explosion that left 15 people dead.
The sources said initial investigations into the case had come with an assumption that it could have been dry run for the blast in September but during the course of probe that the May 25 was a work of a different group all together.
The explosive material used in the May 25 blasts were similar to those used by the terror group on earlier occasions, the sources said and added that "we have some information that would be shared later".
The NIA has re-registered the case under various sections of Explosives Substances Act and Unlawful Activities (Prevention) Act.
The low-intensity blast had taken placed near the footpath of the Delhi High Court boundary wall parking area at Gate number seven and broken eight month lull after a similar explosion near Jama Masjid ahead of the Commonwealth Games in 2010.
The triggering mechanism of May 25 blast remained a mystery for the investigators as it could not be established conclusively so far in the explosion that took place in a service lane outside the court where lawyers' vehicles were parked.
In the September seven blast, NIA had arrested three people while the probe agency was on look out for three more people who were holed up in higher reaches of Kishtawar in Jammu region.