An accidental-death report was filed at the Mumbra police station, and Hiren's death was transferred to the Anti-Terrorism Squad on the basis of an order from the Maharashtra Home Department. A diatom analysis suggested that Hiren was alive when he entered the creek. Hiren's autopsy, performed at Hirenat Chhatrapati Shivaji Maharaj Hospital in Kalwa, did not specify the cause of death but reported multiple abrasions before he died. Later on 5 March, the Hiren death and the bomb scare were transferred to the Mumbai Police Anti-Terrorism Squad. Fadnavis considered this suspicious, and requested a National Investigation Agency (NIA) probe. That day, opposition leader Devendra Fadnavis said that he had telephone records indicating that Assistant Police Inspector (API) Sachin Vaze of the Mumbai Police (the bomb-scare investigating officer until the previous day) had been in contact with Hiren in June and July 2020. His belongings (a phone, a gold chain, and a wallet) were not found. His body, which was floating in the Kalwa creek on the morning of 5 March, wore a face mask with five rolled-up handkerchiefs under it. Mansukh Hiren, the presumed owner of the car (who had filed a police complaint that the vehicle had been stolen), was later found dead. The Jaish-Ul-Hind, a terrorist group formerly unknown to police, denied responsibility after a post in its name on Telegram claimed responsibility for parking the vehicle and seeking a ransom at a non-existent address for the cryptocurrency Monero.

The letter, a mixture of Hindi and English, had several spelling mistakes. The printed letter, addressed to Mukesh and Nita Ambani, said that this was a 'trailer' the explosives would be assembled next time and preparations had been made for the next blast, intended to kill the whole family. A letter was found next to the driver's seat in a bag with the Mumbai Indians logo. Several other number plates were found in the car, some of which matched vehicles in the Ambanis' security team, and one identical to the car used by Nita Ambani. Although they were commercial-grade (not military-grade) explosives, they had the capacity to blow up the car and impact a radius of 350 metres.

The gelatin sticks found in the vehicle (weighing 2.5 kg) were not assembled, and there was no detonator or battery. The vehicle had a false number plate, and the chassis and engine number were scratched. Police were alerted by a call from the Antilia security manager. Since it was in a no-parking zone, Mumbai Traffic Police attached a wheel clamp to it in the morning and generated an electronic fine receipt. Singh wrote a letter to the Chief Minister of Maharashtra alleging that Vaze was operating at the behest of Maharashtra Home Minister Anil Deshmukh, who was also forced to resign after the Bombay High Court directed the Central Bureau of Investigation to inquire into the letter's allegations.Ī green Mahindra Scorpio SUV was parked about 400 metres from Antilia at about 2:00 am on 25 February 2021. As a result, Mumbai Commissioner of Police Param Bir Singh lost his post. Sachin Vaze, a Mumbai Police officer known to Hiren, was arrested for his involvement in placing the explosive-laden vehicle. A week later, Hiren was found dead in a Mumbai creek. The vehicle was traced to Mansukh Hiren, a car-décor shop owner from Thane, who had reported it stolen the previous week.

The bomb scare was notable for the chain of events which followed, forcing several high-profile officials to resign. A note found inside the vehicle, addressed to Mukesh and his wife Nita Ambani, said that the act was a prelude and threatened additional violence. The Antilia bomb scare occurred on 25 February 2021, when a car containing 20 gelignite sticks was found outside the residence of Mukesh Ambani in Mumbai.

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