The latest search and rescue operation in the stretch of sea separating Libya and Italy highlights some of the brutal treatment that female refugees and migrants are subjected to.

More than 2,560 people were rescued in the Mediterranean Sea over the weekend in one of the roughest missions so far this year, the International Organization for Migration said Tuesday. Thirty-four bodies were recovered from the water, 26 of them suspected to be teenagers from Nigeria. Most died while making the crossing toward Italy in rubber dinghies.

IOM believes the girls may have been murdered by traffickers in league with European sex merchants.

Salvatore Malfi, the prefect of the Italian port city of Salerno, was skeptical of this theory but said its too early to come to any conclusion about whether the girls were headed for prostitution. The girls traveled with other men in the dinghy, he said, which makes the theory less likely.

The sex trafficking routes are different, he said. Loading women onto a boat is too risky , the traffickers would not do it as they could lose all their goods as they describe them in one fell swoop.

Italian authorities told CNN that they launched an investigation into the girls deaths Tuesday, carrying out autopsies to determine whether they had been victims of sexual abuse or torture. They were all between 14 and 18 years old, said Salerno police chief Lorena Ciccotti.