The millionaire tech tycoon Mike Lynch’s cause of death has been recorded as drowning after the Bayesian superyacht disaster but his daughter’s cause of death is still under investigation, an inquest has heard. Seven of the 22 people onboard the Bayesian died when it sank in a storm in August. On Friday, inquests into the deaths of the four British nationals – 59-year-old Lynch, his daughter, Hannah, 18, and Judy and Jonathan Bloomer, 71 and 70 – were opened and adjourned at Ipswich coroner’s court. Det Supt Mike Brown, of Suffolk constabulary, said their deaths came after the Bayesian, “for reasons yet to be ascertained, sank rapidly” between 4.15am and 4.45am on 19 August. He said searches began within hours and lasted several days, and the bodies were later found in the vessel’s cabins. The officer said the time of death for all four people was recorded as 5am the same day. Each of the four inquests was separately opened and adjourned until a hearing on 15 April next year. Brown said the Bayesian was 0.8 nautical miles from the coast of the fishing village of Porticello when it sank, and was carrying 12 crew and 10 guests. He told the coroner that Lynch’s provisional medical cause of death was recorded as drowning after a postmortem examination by Prof Antonia D’Argo. Lynch’s death was confirmed on 22 August after his body was found. The officer said the medical cause of death remained under investigation in the cases of Hannah Lynch and the Bloomers, after postmortem examinations by Dr Tommaso D’Anna. The coroner heard that the couple’s deaths were confirmed on 21 August, while that of Hannah Lynch was confirmed two days later after her body was found. Brown said an investigation had been started by the Marine Accident Investigation Branch (MAIB) to understand how the Bayesian sank and the Italian authorities had started their own criminal investigations. Mike and Hannah Lynch both lived in the vicinity of London, while the Bloomers lived in Sevenoaks in Kent, Brown said. The three other people who died were a US lawyer, Chris Morvillo, his wife, Neda, and a Canadian-Antiguan national, Recaldo Thomas, who was working as a chef on the vessel. Brown told Suffolk’s senior coroner, Nigel Parsley, that it would be for the MAIB and the Italian authorities to provide any further relevant material when they were ready. The coroner adjourned proceedings “for further work” to be carried out. Lynch founded the software company Autonomy in 1996. In June this year he was cleared of carrying out a massive fraud over its sale to Hewlett-Packard (HP) in 2011. The boat trip was a celebration of his acquittal in the case in the US.