Two Somali men have been sentenced to life in prison for their roles in a pirate attack on a cruising boat early this year that left four Americans dead, including a Marina del Rey couple, U.S. attorneys said.

U.S. District Judge Mark S. Davis sentenced Ali Abdi Mohamed, 30, and Burhan Abdirahman Yusuf, 31, both of Somalia, Aug. 22 in the deaths of Jean and Scott Adam, of Marina del Rey, and Phyllis Macay and Bob Riggle of Seattle, according to the U.S. Attorney’s Office Eastern District of Virginia. The four Americans were murdered by a group of Somali pirates Feb. 22 while making a passage towards Oman in the Arabian Sea on the Adams’ 52-foot S/V Quest.

The Adams, who were members of the Del Rey Yacht Club in Marina del Rey, had been traveling around the world and were passing out bibles along the way before their boat was overtaken by pirates and they were held hostage with Riggle and Macay.

Mohamed and Yusuf pled guilty to piracy, which carries a mandatory life sentence, a U.S. attorney spokesperson said. Nine co-conspirators have also pled guilty and will be sentenced in the coming weeks. Three men – Ahmed Muse Salad, 25; Abukar Osman Beyle, 20; and Shani Nurani Shiekh Abrar, 29 – have been charged in a 26-count superseding indictment with the kidnapping, hostage-taking and murder of the four U.S. citizens onboard the Quest, according to the U.S. Attorney’s Office.

“Piracy is a scourge that threatens nations, commerce, and individual lives,” said Neil MacBride, U.S. attorney for the Eastern District of Virginia. “This is the first case where American lives have been lost due to Somali piracy, and as Somali pirates expand their territory, the risk of violence and harm to others continues to grow. The sentences send a message to all those who participate in piracy that armed attacks on the high seas carry lifelong consequences.”

The investigation of the case is being conducted by the FBI and the Naval Criminal Investigative Service.