A careful perusal of CCTV footages at the Chennai Central Station, Bangalore City Railway station and those between Bangalore and Chennai has led the CB-CID police, probing the explosion to zero in on some "positive" leads, a senior official involved in the investigation said here.
He said "some more suspects have been identified" but declined to elaborate, saying it would hamper investigations.
The CB-CID police have sought the help of experts to confirm whether a suspect who boarded the Bangalore-Guwahati express at Bangalore and who was masking his face with handkerchief, was the same person who was seen hurriedly alighting at Chennai, the official said.
Police are also looking at the possibility of the blasts being the handiwork of Indian Mujahideen or some sleeper cells, he said.
The CB-CID has also deputed a team to Patna against the backdrop of investigations indicating that explosions there hours before Narendra Modi's "Hunkar" rally, was similar to that of Chennai blast.
24-year-old woman techie Swathi, hailing from Guntur, was killed and 14 people were injured in the low-instensity twin bomb blasts on May day.