ROME—An Italian investigation into the shipwreck of the Costa Concordia is looking into phone calls between the captain and the ship's operator just as the liner started to sink, according to people familiar with the probe.
The information may shed light on why it took more than an hour to order the evacuation of more than 4,000 people aboard, a delay that frustrated rescue efforts and sowed panic among passengers.
The probe into the shipwreck—which has so far claimed 11 lives and leaves 21 more people unaccounted for five days later—is focusing on the measures Captain Francesco Schettino took as the vessel crashed against rocks near the Tuscan island of Giglio. After impact, the captain steered the ship closer to shore. But for reasons that remain unclear, he delayed evacuation measures and didn't call the coast guard. It was only after at least four coast guard calls to the ship that the ship sounded its evacuation alarm.
Prosecutors are trying to understand whether ship operator Costa Crociere, a unit of Carnival Corp., was advising the captain on how to handle the emergency as it was unfolding, according to the people familiar with the probe.
Costa Crociere spokesman Davide Barbano said the company preferred not to comment as the investigation is under way. But Roberto Ferrarini, Costa Crociere's director of marine operations, said Mr. Schettino was following protocol in making the call.
The wreck of the Costa Concordia on Friday has gripped Italy, a country flanked by water on three sides and with bustling shipping ports and a rich naval history. Images of the gigantic, half-sunk vessel have filled newspaper pages, newscasts and talk shows. For many, the incident—how the ship veered off course, the international images of its foundering, the struggle over who would take initiative to save those aboard—has become emblematic of Italy, which is struggling to right itself after a decade in the economic doldrums.
The role of Mr. Schettino, Concordia's 52-year-old captain, has raised particular passions. Recordings of phone conversations between Mr. Schettino and a coast guard commander in the hours following the shipwreck portray the captain as making excuses for leaving his ship as passengers remained aboard, saying he preferred to "coordinate" evacuation efforts from a lifeboat.
Italian media have lionized Gregorio De Falco, the coast guard commander who can be heard upbraiding Mr. Schettino over the phone. One of Mr. De Falco's more colorful Italian-language urgings—which translates, roughly, as "Get back on board, damn it!"—has been printed on T-shirts for sale on the Internet.
Other heroes, too, have emerged, including the drummer of the ship's band, who ceded his seat on a lifeboat to a young boy and is now missing, and an officer who helped several people and broke his leg.
"This affair has become, to the outside world, emblematic of Italy," said Enrico Mentana, anchor of one of Italy's main newscasts, as he introduced Wednesday's evening news. "We see ourselves as the good commander, rather than the bad captain. But the outside world sees the opposite in us."
On Tuesday, an Italian judge in the Tuscan town of Grosseto ordered Mr. Schettino to be placed under house arrest in his hometown near Sorrento on preliminary charges of multiple manslaughter, failure to assist passengers in need and abandonment of ship. Under questioning from the judge, the captain said he deviated from the ship's official route to get closer to the island of Giglio, a move that caused the ship to collide with the rock formation, according to a copy of the ruling issued Wednesday.
Mr. Schettino told the judge he was "on the phone at that moment" with a colleague on the island who he wanted to "salute" by steering the ship close to the port and blasting the ship's horn. Mr. Schettino also said he wasn't using the ship's computer navigation system.
"I was navigating by sight, because I knew those sea beds well. I had done the move three, four times," he said, according to an excerpt of his closed-door deposition, confirmed by a person familiar with the matter.
Some in Italy are starting to coming to Mr. Schettino's defense. Italian newspapers published a photo of a huge banner, flying on a street in the captain's hometown, with the words: "Captain, Don't Give Up." Bruno Leporatti, Mr. Schettino's lawyer, lamented the demonization of his client, saying he could "only express my disappointment."
During a news conference on Monday, Costa Crociere's chief executive, Pier Luigi Foschi, said the company didn't authorize Mr. Schettino to deviate from the ship's official route. He said the company had given approval for a Costa ship to steer close to the port of Giglio once, at the end of last summer. Mr. Barbano declined to comment further on the deposition.
During the news conference, Mr. Foschi also touched upon the company's contact with the captain the night of the wreck. Roberto Ferrarini, Costa Crociere's director of marine operations, spoke by phone to Mr. Schettino at about 10:05 p.m. Friday. Mr. Schettino told Mr. Ferrarini the ship was dealing with an "emergency that had not yet been identified," Mr. Foschi said.
Since Mr. Foschi made those comments, on Monday, Italian authorities disclosed a timeline, noting Mr. Schettino's ship stuck the rock formation at 9:45 p.m., 20 minutes before he called Mr. Ferrarini. The ship sounded its evacuation alarm at 10:58, according to Italian officials. Mr. Ferrarini didn't respond to an email seeking comment
In between Mr. Ferrarini's contact with the ship and the evacuation, the Italian coast guard received complaints from passengers aboard the ship and made a series of phone calls to the ship's command, seeking clarification on whether the Costa Concordia was in distress.
At 10:14 p.m., the ship's command answered that the vessel had only suffered a power outage, according to the Italian officials, even though seawater was already rushing through the gash in its hull, flooding the engine room.