Bharat Bhusan Katariya, a senior scientist with the Defence Research Development Organisation (DRDO), was reportedly behind the blast at a court in Delhi earlier this month. The scientist allegedly installed the explosive to target his neighbour, a lawyer he has had 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.
The police said that ammonium nitrate was used to prepare the explosive device, adding that the material is easily available.
The police added that only the detonator exploded and the explosive did not, saying it would have been a larger explosion otherwise.
The laptop bag in which the explosive was placed had the logo of a Mumbai-based firm that has a storehouse in Delhi, the police said, adding that the firm helped them with the probe. Files in the bag also helped in the investigation.
Katariya, a senior scientist with the DRDO, has been arrested and bomb-making material recovered from his residence. According to the police, he entered the court in the guise of a lawyer.