Prosecutors in Sicily have broadened their investigation into the sinking of the luxury yacht, the Bayesian, and are now looking into the actions of two more crew members, their lawyer said Thursday.

The captain of the yacht, James Cutfield, is also facing a manslaughter inquiry to determine whether his actions negligently caused the shipwreck, one of his lawyers said Tuesday.

Seven people — six passengers and one crew member — died in the Aug. 19 accident amid a pre-dawn storm off the coast of Sicily. Among the victims was the British tech entrepreneur Mike Lynch, whose family owned the Bayesian, as well as his 18-year-old daughter Hannah.

On Wednesday, prosecutors placed under investigation Tim Parker Eaton, who was in charge of the Bayesian’s engine room, and Matthew Griffiths, the crew member who was on lookout duty that night. They are both represented by Marco Scopesi, a lawyer based in Genoa, who confirmed that the two men were under investigation.

In Italy, placing someone under formal investigation does not necessarily mean criminal charges will follow.

The cruise was to celebrate Mr. Lynch’s acquittal in June on charges that he had led one of the biggest frauds in the technology industry by vastly inflating the value of a company he had founded when he had sold it to Hewlett-Packard for $11 billion in 2011. This summer, he had scheduled several cruises to thank the lawyers who had helped him win the case.