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 dispute 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.
Bharat Bhushan Katariya, a senior scientist with the DRDO, has been arrested and bomb-making material recovered from his residence, police said.
According to police, he entered the court in the guise of a lawyer and escaped after the blast.
The investigation has found that Katariya and his neighbour and lawyer Amit Vashisht had an old dispute and had filed several cases against each other over several matters, including water supply.
Police said Katariya allegedly planted the explosive at court to kill Mr Vashisht, who was appearing in court that day.
It is now being investigated how the accused managed to take explosives inside the court premises. Police have found that the accused bought the remote used to set off the bomb and some other material from an e-commerce website. It is now being investigated where he arranged the explosives from.