Police say a scientist from the Defense Research and Development Organization (DRDO) was behind the blast at a court in Delhi earlier this month. The scientist is said to have installed the explosives targeting his neighbor, who had an old dispute.
Speaking to reporters, Delhi Police Commissioner Rakesh Asthana said the special team investigating the matter had inspected the 1,000 vehicles that arrived at the Rohini court that day and scanned the footage of more than 100 CCTV cameras.
The inquiry team also visited the hearings held that day and those who attended the court.
Ammonium nitrate was used to make the ammunition, and the substance was readily available, police said.
Police said only the detonator exploded and the explosive did not explode, otherwise it would have been a huge explosion.
The laptop bag in which the explosives were kept had the logo of a Mumbai-based company with a coupon in Delhi, which the company assisted in the investigation, police said.
Police have arrested DRDO senior scientist Bharat Bhushan Kataria and recovered bomb-making materials from his house.
Police say he entered the courthouse in the guise of a lawyer and escaped after the bombing.
The investigation has revealed that the old dispute between Kataria and her neighbor and lawyer Amit Vashisht came from several cases involving each other in various matters including water supply.
Police said Kataria allegedly put ammunition in court to kill Mr Vashisht, who appeared in court that day.
An investigation is currently underway into how the accused took the ammunition into the court premises. Police have found that the accused bought the remote and other items used to detonate the bomb from an e-commerce website. An investigation is underway into where he arranged the explosives.