Some of the Sicily Yacht Sinking Victims May Have Suffocated After Air Pocket Ran Out, More Testing Needed: Sources

Seven people were killed when the luxury vessel, carrying 12 passengers and 10 crew, sank amid severe weather off the coast of Sicily last month

More testing will be needed to determine how some victims died in the Sicily yacht sinking last month, a source tells PEOPLE.

Preliminary autopsy results on Chairman of Morgan Stanley International Jonathan Bloomer and his wife, Judy Bloomer, “show they died from suffocation,” says the source, who is close to the investigation of the sinking.

However, tests on their tissues are now underway to definitively determine whether or not the couple died of suffocation because an air bubble in the yacht cabin they were in ran out of oxygen and filled with carbon dioxide, the source says, or if breathing in water was the cause.

Related: Sunken Yacht's Crew Reveals What They Say Happened Before Tragedy: 'Thrown Into the Water' and 'Walking on the Walls'

Sources tell PEOPLE the tests could take as long as a few weeks to be carried out and for the results to be released.

The Bloomers were among seven people who died when the luxury yacht Bayesian sank off the coast of Porticello early on Aug. 19 amid severe weather, officials have said.

Twenty-two people were onboard — 12 passengers and 10 crew — and the seven victims included the Bloomers; New York City-based lawyer Christopher Morvillo and his wife, jewelry designer Neda Morvillo; British tech businessman Mike Lynch and his daughter Hannah; and the yacht’s chef, Recaldo Thomas.

Autopsies for the Lynches and Thomas will be conducted on Friday, the source close to the investigation confirms to PEOPLE.

On Monday, Sept. 2, the Associated Press and Italian news agency ANSA reported that the autopsies of Christopher and Neda Morvillo ruled their cause of death as drowning.

In the days since, however, some uncertainty has been raised about exactly how the six victims suffocated in their cabins. (The seventh victim, Thomas, the chef, was found outside the Bayesian.)

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CNN and the La Repubblica newspaper reported that the initial autopsies done on the four victims so far indicated they were killed by “atypical drowning” and, according to La Repubblica, the Bloomers and the Morvillos “had no water in their lungs, trachea, or stomach.”

Reuters reported that the initial autopsies of the four victims so far "indicated they had died of suffocation as oxygen ran out on the stricken vessel" but "[m]ore forensic tests were ordered."

Sources caution to PEOPLE that this examination and testing will need to be done before it is confirmed how those victims suffocated.

Other causes of death have been ruled out.

Medical experts say that in some cases of drowning, water doesn't enter the lungs because of an involuntary reflex in the throat, leading to suffocation.

So-called "dry drowning" is not a medically preferred term as water is always a factor in these cases.

Girolamo Bentivoglio Fiandra, head of the Palermo Fire Brigade, spoke at a news conference last month as the yahct victims were formally identified and shared details of their final moments and where they were recovered.

“It was quite clear that people [inside] were trying to hide in the cabins. In the left-hand side, we found the first five bodies in the left-hand side cabins, and the final body on the right-hand side. We found them on the highest part of the ship which was closer to the surface. The vessel had three cabins on each side,” Fiandra said then.

Related: Captain Who Saw Sicily Yacht Sink Says Mike Lynch’s Wife Didn’t Want to Leave Scene Without Husband and Daughter

He also said that the five who "took refuge in the cabins on the left side of the sailboat" had been "searching for air pockets."

A broader investigation is ongoing into how, exactly, the Bayesian sank in August — in what some witnesses have said was a quickly unfolding tragedy that has puzzled observers, given the yacht’s size and apparent capability to withstand bad weather.

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