A scientist with the Defence Research Development Organisation (DRDO) was behind the blast at a court in Delhi earlier this month, the police have said. The scientist allegedly installed the explosive to target his neighbour, a lawyer he has had an old enmity with.
Addressing the media, Delhi Police commissioner Rakesh Asthana said the Special Cell team investigating the matter examined 1,000 vehicles that came to the Rohini court that day and scanned footage from more than 100 CCTV cameras.
The probe team also went through the hearings held that day and those who visited the court.
Ammonium nitrate was used to prepare the explosive device, police said, adding that the material is easily available.
Police added that only the detonator exploded and the explosive did not, adding that it would have been a much larger explosion otherwise.
The laptop bag in which the explosive was placed had the logo of a Mumbai-based firm that has a godown in Delhi, police said, adding that the firm helped them with the probe.
Files in the bag also helped in the investigation, they said.
Bharat Bhushan Katariya, a senior scientist with the DRDO, has been arrested and bomb-making material recovered from his residence.
According to police, he entered the court in the guise of a lawyer.