Mohammed Ali Malek, the 27-year-old captain from Tunisia, faces the same prospective charges as one of his crew members, 26-year-old Mahmud Bikhit of Syria, according to a news release from the prosecutor's office in the Sicilian city of Catania.
Authorities there plan to ask a judge Tuesday to keep both men jailed as the case against them continues. A lawyer has been appointed for the men and on Friday a judge will hold a hearing and listen to the accounts of five witnesses, the prosecutor's office said.
That's one of two possible causes that investigators have considered, the other being that the migrant ship tipped over after everyone ran to one side of it.
There's no indication that the King Jacob cargo ship, which went to the aid of the migrant boat, had anything to do with its sinking. To the contrary, Salvi's office said the vessel "dutifully provided relief (and) did not contribute in any way to the fatal event."
"Only the commander of the fishing vessel and its crew are suspected of causing the crime," the Catania prosecutor's office said.
20-meter boat had about 850 aboard
This revelation comes hours after a U.N. official said, based on accounts from survivors, that the King Jacob could have caused the other vessel's capsizing either by touching it or by producing a big wave that led it to tip roughly 70 miles (110 kilometers) north of Libya.
Those were two of three possibilities outlined by Carlotta Sami, a spokeswoman for the United Nations refugee agency, to CNN early Tuesday. The other was that the 20-meter (66-foot) boat was simply overcrowded, with about 850 people packed aboard.
Mark Clark -- a communications executive representing OSM Maritime Group, the company that manages the King Jacob -- denied the cargo ship caused the migrant boat to capsize.
The cargo ship was going very slowly as it approached, hardly making any waves before deploying rescue boats, a gangway, nets and life rings to help, he told CNN.
The King Jacob, whose crew members are all from the Philippines, ended up saving 22 survivors, according to Clark.
Italian authorities have said that in all, 28 people were rescued.
That leaves hundreds more presumed dead.
Locked in lower part of the ship, survivor says
Dr. Giuseppe Pomilla, an Italian physician working with the Knights of Malta, was aboard the coast guard vessel that rescued the migrants and described the nightmarish scene.
"My colleague Enrico (a nurse) and I got onto dinghies to find survivors," he said. "What we saw, is terrible to say. It was a carpet of bodies. We switched off the engine of the dinghies and we heard some terrific screams.
"We lighted some areas of the sea with (spotlights). In the distance we saw a man that was waving at us, asking for help. We got close to him and got him on board. He was really happy. We spoke with him in English, we told him we were Italian and that we were there to save him. He told us we were his best friends.
"Then we saw another man -- we didn't know if he was dead or alive. He was staring to us from the sea, his eyes wide open. He couldn't close his eyes, he couldn't talk. He just grabbed our arm and we got him on board. He still didn't talk, and when we arrived on the Gregoretti (the coast guard vessel) he started crying."
About 24 bodies had been recovered as of Monday. The vast majority of the victims are believed to be still inside the sunken boat.
Those who made it out alive were on all on the highest part of the overcrowded vessel. Italian authorities said Sunday that an unidentified Bangladeshi survivor had told them that smugglers had locked many more people inside the lower decks.
According to the Catania prosecutor's office, these lower compartments flooded immediately.
Francesco Rocca, the president of Italy's Red Cross, said all of those rescued so far were men, most of whom were in their 20s and 30s. They include one man from Gambia, who is the lone survivor in a group of about 80 of his countrymen.
"They are completely shocked," Rocca said of the survivors.
"Our psychologists are working hard with them," he added, describing it as a tragedy many times over. "They lost a lot of friends."
Mediterranean migrant deaths skyrocket
The likely toll makes the sinking the deadliest known disaster involving migrants crossing the Mediterranean from North Africa.
Still, while it is historic, it's not necessarily surprising. The sinking is part of an escalating problem of people putting their lives in the hands of human traffickers, feeling that's a better option than the despair they're leaving behind.
At least 1,776 people have died or gone missing this year in the sea that touches Europe, North Africa and parts of the Middle East, according to the U.N. refugee agency.
By comparison, some 96 people had died in the Mediterranean at this point last year.
Some 36,390 people have managed to safely reach Italy, Greece or Malta in the first few months of 2015, UNHCR spokeswoman Melissa Fleming said Tuesday on Twitter.
More Syrians -- nearly 9,000 -- are taking to boats to find refuge than citizens of any other country, something that's perhaps not surprising given that country's ongoing civil war
The other countries where the most migrants have come from are Eritrea, Somalia, Afghanistan and Nigeria.
According to witnesses accounts, the capsized boat sailed from a town near Tripoli on April 16, the Italian prosecutor's office said Tuesday in a statement.
The migrants had been kept on a farm near the place of departure and were transported in vans to the boarding area, the statement said. The cost of transport, according to witness accounts, was 500 to 1,000 Libyan dinars (about $365 to $730) per person.
The prosecutor is trying to determine the exact number and identities of victims. The prosecutor's office is asking families and people who knew the victims to send an email to: firstname.lastname@example.org.
Can Europe handle this crisis?
Their destination -- or, at least, their next planned stop -- was Europe. But is the continent ready for the wave of migrants? Can its leaders curb the exodus? And can they do more to prevent more boats sinking and more people dying?
Those are the types of questions many are asking now.
After meeting Monday in Luxembourg, European Union ministers agreed on "the need to increase significantly the resources at sea, and the level of the operation, doing more search and rescue and doing it more together," according to an EU official.
"We need to fight the organizations that are trafficking and smuggling people, so that we can prevent desperate people from leaving in desperate conditions," said Federica Mogherini, the EU high representative for foreign affairs and security policy. "My pain is that it was a reaction coming too late after so many people died."
Matteo Renzi, the Italian Prime Minister, posted a message on his official Facebook page calling for cooperative actions.
"Demagogy does not help," he said. "If we really finally see that the written words are accompanied by concrete action, that will be a first step for Europe," he said.
The frustration in some quarters is readily apparent.
"With each day we delay we lose more innocent lives and Europe slips further into an immoral abyss," Justin Forsyth, the chief executive of Save The Children, said in a statement. "Right now, people desperately seeking a better life are drowning in politics."
Shipping companies recently warned that they're carrying an unfair burden.
Commercial ships rescued more than 40,000 people in the Mediterranean last year, according to the International Organization for Migration. That's higher than the more than 35,000 people saved by the Italian coast guard but lower than the 80,000 rescued by the Italian navy, which was running a special program, Mare Nostrum
, for most of the year.
In a letter to EU leaders last month
, the European Community Shipowners Associations said "commercial ships are not equipped to undertake such large-scale rescues, which also create serious risks to the safety, health and welfare of ships' crews who should not be expected to deal which such situations."
"We believe it is unacceptable that the international community is increasingly relying on merchant ships and seafarers to undertake more and more large-scale rescues, with single ships having to rescue as many 500 people at a time," the group said.
Not all the migrants travel on cargo ships.
On Monday Italian police said they arrested three crew members who carried 99 migrants, including 23 children, on an "old luxury yacht."
Police said the migrants could afford to pay 8,500 euros ($9,146) per passenger while pretending to be tourists. The boat was stranded at sea due to an engine problem and was rescued by a mercantile ship. It was taken to the port of Pozzallo in Sicily.