Prosecutors in Palermo issued arrest warrants for 13 people — seven Tunisians, five Moroccans and an Italian woman — suspected of people smuggling and trafficking in contraband cigarettes, according to a copy of the document seen by Reuters.

Phone intercepts showed migrants paid between 3,000-5,000 euros ($3,700- $6,160) for the high-speed trip that brought them surreptitiously to Italy in just a few hours, allowing them to avoid being taken to refugee centers and finger-printed.

“We cannot rule out that dangerous people might have taken advantage of this system, although we do not have any precise information about this,” said Palermo’s head prosecutor, Francesco Lo Voi.

In one intercept, a man is heard telling the organizer of a migrant crossing that he planned to travel onto France to carry out “dangerous work from which he might not return”, the prosecutors said in a statement.

In a similar case last June, Palermo magistrates arrested 15 people who were suspected of organizing at least five crossings between Tunisia and Sicily, earning an estimated 40,000 euros for each trip.

Prosecutors said on Wednesday the new gang made between 30,000-70,000 euros for each crossing.

More than 600,000 migrants have come to Italy since 2014, but most of them pay far less to Libya-based smugglers (usually between $800 and $1,300) to board overcrowded and unseaworthy boats for a voyage that often ends in tragedy.

An estimated 521 migrants have died this year trying to reach Italy, according to the International Organisation for Migration (IOM), while some 6,894 people made it there safely and were then registered in Italy’s official immigration system.