The bodies of the four remaining Italian scuba divers who drowned in an underwater cave in the Maldives returned to Italy Saturday — as Roman prosecutors ramp up the manslaughter investigation amid mounting questions over who decided to take the group so deep without the right equipment.

Monica Montefalcone, a marine biologist from the University of Genoa, her daughter Giorgia Sommacal, researcher Muriel Oddenino, and recent graduate Federico Gualtieri were repatriated on an overnight Turkish Airlines flight that stopped over in Istanbul, Il Giornale reports.

They arrived at Milan’s airport around 1:15 p.m. local time.

After landing, the coffins containing the four bodies were seen covered in plastic wrap and loaded on a tow tractor on the runway, before being taken to the morgue of the hospital in Gallarate, 25 miles outside Milan, where the autopsies will be conducted.

Montefalcone’s and Gualtieri’s bodies were recovered Tuesday by an elite squad of Finnish divers, and Sommacal’s and Oddenino’s were pulled out of the water Wednesday.

They were all found in the cave’s third and deepest chamber with empty oxygen tanks.

The fifth diver, diving instructor and boat captain Gianluca Benedetti, was found May 14, the evening of the tragedy, away from the group near the mouth of the cave in the first chamber, before the search was called off because of bad weather.

His body arrived on a repatriation flight to Milan Tuesday, and an autopsy is scheduled for Monday.

Autopsies for the other four will be conducted over the following days, with a coroner, a toxicologist and an anesthesiologist specialized in diving medicine, Luciano Ditri, one of the leading Italian experts in hyperbaric medicine, enlisted by the prosecutors.

Gualtieri’s family has also hired its own forensic pathologist.

The five Italians vanished during a deep-water dive inside a cave 164 feet underwater in Vaavu Atoll in what officials called the worst diving accident in the island nation’s history.

Rome’s prosecutor’s office is investigating the case as a culpable homicide, the Italian legal equivalent of manslaughter.

Part of the probe is to determine why the group of experienced divers went below the Maldives legal recreational diving limits of 100 feet without the required training, permit or equipment.

They’re believed to have run out of oxygen after getting lost in the cave, according to the Finnish rescuers, who said visibility drops drastically as one goes further inside and sunlight stops shining — and a small kick from diving fins as the divers try to move inside the tight space is enough for sediment from the bottom of the ocean to cloud the view.

Why Benedetti, 44, was away from the group is also a mystery. It’s believed he may have been trying to escape but ran out of air before he could resurface.

Both the Italian boat operator, Albatros, and the University of Genoa, who sent some of the researchers to the Maldives on a scientific mission, were quick to distance themselves from the tragedy — saying they had not authorized the deep dive and it was not planned.

Italian investigators have questioned three University of Genoa professors, including one, Stefano Vanin, who was on the boat — the Duke of York, which has since had its license suspended by the Maldives government — but did not take part in the tragic dive.

They’ve also been handed the recovered diving equipment, including GoPros, that might provide clues to what happened.