Specialist divers surveying the wreckage of the $40 million superyacht that sank off Sicily in August, killing eight people including British tech tycoon Mike Lynch, have asked for heightened security to guard the vessel, over concerns that sensitive data locked in its safes may interest foreign governments, multiple sources told CNN.

Italian Prosecutors who have opened up a criminal probe into multiple manslaughter and negligent shipwreck think the 56-meter (184-foot) yacht, the Bayesian, may contain highly sensitive data tied to a number of Western intelligence services, four sources familiar with the investigation and salvage operation said.

Lynch was associated with British, American and other intelligence services through his various companies, including the cyber security company he founded, Darktrace.

That company was sold to Chicago-based private equity firm Thoma Bravo in April. Lynch, whose wife’s company Revtom Limited owned the vessel, was also an adviser to British prime ministers David Cameron and Theresa May on science, technology and cyber security during their tenures, according to British government and public Darktrace records.

The sunken vessel, lying on the seabed at a depth of some 50 meters (164 feet), is thought to have watertight safes containing two super-encrypted hard drives that hold highly classified information, including passcodes and other sensitive data, an official involved in the salvage plans, who asked not to be named, told CNN. Specialist divers with remote cameras have searched the boat extensively.

Initially, local law enforcement feared that would-be thieves might try to reach the wreckage to find expensive jewelry and other objects of value still onboard the yacht, according to divers with the Fire Brigade who spoke with CNN. Now they are concerned that the wreckage, expected to be raised in the coming weeks as part of the criminal investigation into the tragedy, will also be of interest to foreign governments, including Russia and China. They have requested that the yacht be guarded closely, both above water and with underwater surveillance.

“A formal request has been accepted and implemented for additional security of the wreckage until it can be raised,” Francesco Venuto of the Sicilian Civil Protection Agency confirmed to CNN.

Lynch, his 18-year-old daughter Hannah, American attorney Chris Morvillo and his wife Neda, British banker Jonathan Bloomer and his wife Judy, and the yacht’s onboard chef Recaldo Thomas died when the ship sank in a violent storm in the early hours of the morning.

Preliminary results from autopsies suggest that the Bloomer and Morvillo couples died of suffocation or “dry drowning” when the oxygen in an air bubble in a sleeping cabin ran out. Autopsy results for Lynch and his daughter were less clear.

The chef, whose body was found outside the vessel, died by drowning, the coroner said. Toxicology reports on the dead have not yet been released, but none had suffered any physical injuries when the boat went down.

Lynch’s wife Angela Bacares and 14 others survived, including the captain James Cutfield, who, along with a deckhand and the yacht’s engine room manager, is under investigation for multiple manslaughter and causing a negligent shipwreck. They have all been allowed to leave Italy.

Some of the 15 survivors, of whom nine were crew members and six were passengers, including a 1-year-old girl, reportedly told prosecutors that Lynch “did not trust cloud services” and always kept data drives in a secure compartment of the yacht wherever he sailed, a source with the prosecutor’s office told CNN. None of the crew or passengers who survived the incident were tested for drugs or alcohol because they were in a “state of shock,” authorities said during a news conference following the recovery of the bodies.

Morvillo represented Lynch when he was acquitted in a criminal fraud case in the US in June tied to the takeover by Hewlett Packard of his software company Autonomy, and survivors told investigators that the cruise was a celebration of that acquittal, according to the assistant prosecutor, Raffaele Cammarano. Though Lynch was acquitted of any criminal wrongdoing in the US, Hewlett Packard has indicated it will not drop its bid to collect a $4 billion civil payout from Lynch’s estate, awarded by a British court in 2022.

In what appears to be a tragic coincidence, Lynch’s business partner Stephen Chamberlain — who was his co-defendant in the US fraud case and the former chief operating officer of Darktrace — died on August 19, the same day the Bayesian sank, after being hit by a car while out jogging two days earlier. A spokesperson for the prosecutor’s office told CNN that Cutfield told them Lynch had learned of Chamberlain’s serious condition and had planned to cut the cruise short to return to the UK to see his business partner, who had been on life support.

The Bayesian sank a few hours before Chamberlain died in the hospital, his lawyer said. Lynch would not have known of his partner’s death, and Chamberlain was in a coma so would not have known about the shipwreck, Chamberlain’s legal counsel said.

Local prosecutor Ambrogio Cartosio said no personal effects, including computers, jewelry or Lynch’s hard drives had been recovered from the vessel. However, the onboard hard drives and surveillance cameras tied to the yacht’s navigation system have been brought to investigators to determine if there is any usable data that might indicate how the yacht sank within 16 minutes of the storm hitting. The vessel did not have a traditional black box or voyage data recorder to record navigation data or audio on the bridge.

After divers complete surveys of the wreck this week, they will make suggestions for how to best raise the 473-ton vessel without spilling any of the 18,000 liters of oil and fuel still onboard, and how to make sure any sensitive data does not fall into the wrong hands. The costs of raising the ship will fall to its owner, Lynch’s widow, as is mandated by Italian maritime law.