Divers have pulled a woman's body from the sinking cruise ship, Costa Concordia, on Sunday, raising the number of dead to 13. The cruise ship ran aground on Jan. 13 off the Tuscan island of Giglio.

The Associated Press reported that civil protection official Francesca Maffini told reporters that the victim was wearing a life vest. A team of department divers found the unidentified body in the rear of a submerged portion of a ship, The AP article stated.

Approximately 20 people were missing before the body was found and officials in Italy have told the media that there is a possibility that unregistered passengers were on board when the Concordia hit a reef and began sinking. Eight of the 13 bodies have been identified thus far, The AP reported.

There could have been X persons who we don't know about who were inside, who were clandestinepassengers aboard the ship, Franco Gabrielli, the national civil protection official in charge of the rescue effort, told reporters at a briefing on Giglio.

Costa Concordia, a luxury cruise ship, had 4,200 people on board when in slammed into the reef, ripping a hole into its hull. The Italian captain, Francesco Schettino, has been placed under house arrest. Prosecutors have accused him of suspected manslaughter, causing a shipwreck and abandoning the ship before everyone were evacuated.

The cruise ship operator has said Schettino made an unauthorized deviation from the vessel's route in order to impress passengers and sailed the ship too close to the island.

Audio from the ship details that coast guard officials had ordered Schettino back on the ship to coordinate rescue operations. Schettino has denied abandoning the ship while passengers were still on board and has said he coordinated the rescue from aboard a lifeboat and then from the shore, according to The AP.