The family of British tech entrepreneur Mike Lynch and his daughter Hannah, who died on Monday when their yacht sank off the coast of Sicily, say they are devastated and in shock.

They spoke of their “unspeakable grief” when the last body from the sunken Bayesian yacht was recovered on Friday, reportedly 18-year-old Hannah.

“Their thoughts are with everyone affected by the tragedy,” a statement from the family said. “They would like to sincerely thank the Italian coastguard, emergency services and everyone who helped in the rescue operation.”

Italian authorities are investigating the circumstances surrounding Monday’s sinking of the boat, which also killed five other people on board.

Family and friends paid tribute to Mr Lynch, who was a pioneer in the field of artificial intelligence, and to his daughter, who had just been admitted to the University of Oxford.

“Mike was the most brilliant mind and caring person I have ever known,” said close friend Andrew Kanter. “His passion for life, knowledge and everyone around him immediately inspired everyone he met, and he will be deeply missed.”

Gracie Lea, a classmate of Hannah’s, described her as “easy to love: sincere, devoted, fiercely intelligent and genuinely kind. I will always remember her smile.”

According to the Times, she had recently completed her A-levels and had been offered a place to study English at Oxford.

“We are all absolutely devastated by the news,” said a spokesperson for her school, Latymer Upper, in west London.

“Our thoughts are with their families and everyone involved,” they added.

Among those killed in the disaster were Jonathan Bloomer, chairman of Morgan Stanley International, and his wife Judy, a charity board member.

In a statement, the Bloomer family described the couple as “incredible people and an inspiration to so many.”

Also killed in the disaster were Clifford Chance attorney Chris Morvillo, his wife Neda Morvillo and the boat’s cook, Recaldo Thomas.

Among the 15 survivors were a one-year-old child and Hannah Lynch’s mother, Angela Bacares.

Italian authorities are still investigating the circumstances surrounding Monday’s incident.

In cases like these, it is common for officials to launch a full-scale investigation — called a “crime hypothesis” — that considers a range of possible criminal charges.

Italian police were contacted by BBC News and confirmed that an investigation is underway, but no charges have been filed.

The yacht’s captain, James Cutfield, its eight surviving crew members and passengers have been questioned by the Coast Guard on behalf of the Public Prosecution Service.

Rescue workers described the search and recovery operation as “complex”, with divers limited to 12 minute underwater shifts.

In a statement, Italian firefighters said it involved “five days of long and delicate operations in the sea, at a depth of about 50 meters (about 164 feet).”

After reports emerged that the last body had been found, a coast guard vessel that had been at the site of the shipwreck for hours was seen back in the harbor.

Meanwhile, a helicopter landed nearby, while divers on the dock took off their orange suits.

An Italian coastguard spokesman said a decision on whether to raise the sunken yacht from the seabed was “not on the agenda” but would only be made in the future.

According to search and rescue divers, the ship lay “virtually intact” on the seabed.

Prosecutors are expected to hold a press conference on Saturday morning.