Two more Somali men pleaded guilty on Monday to piracy for their roles in the hijacking of a yacht that left four Americans dead, including one who identified which of the 19 men fired at hostages aboard the boat.

Burhan Abdirahman Yusuf and Jilani Abdiali face mandatory life sentences, but as part of a plea agreement they could serve less time than that and eventually be deported to Somalia.

The duo are among 14 people from Somalia and one from Yemen facing charges related to the February hijacking of the yacht Quest. Three of those men have already pleaded guilty to piracy in plea deals.

The owners of the Quest, Jean and Scott Adam of Marina del Rey, Calif., along with friends Bob Riggle and Phyllis Macay of Seattle, were shot to death several days after being taken hostage several hundred miles south of Oman.

They were the first U.S. citizens killed in a wave of pirate attacks that have plagued the Gulf of Aden and the Indian Ocean in recent years. Prosecutors said the men intended to bring the Americans to Somalia and hold them for ransom there. Pirates typically seek millions of dollars for hostages.

In a statement of facts Yusuf agreed to Monday, Yusuf said the 19 men who had taken control of the yacht would have split 65 percent of the ransom money among themselves and an interpreter. The other 35 percent would be given to a financier. In Abdiali's statement of facts, he said he saw that pirates were making a lot of money and had big houses and cars, so he spoke with a financier about joining a pirate expedition that ultimately led him to board the American yacht.