Police reports indicate that the suspects assembled the IEDs at Rizwan's residence in Batla House. After the first device failed to detonate effectively at Yamuna Bank, they refined their approach, adjusting the temperature and chemical concentration before testing in Haldwani and Nuh. In Haldwani, they detonated a larger IED in a secluded jungle area, avoiding detection by locals. Their experiments continued in Nuh, where they successfully attached a cylinder to the IED and set a five-minute timer.
