According to the indictment, the men face kidnapping, firearms and piracy charges in their attempt to hold the yacht's passengers for ransom.
The yacht's owners, Jean and Scott Adam of Marina del Rey, along with friends Bob Riggle and Phyllis Macay of Seattle, were shot to death after pirates took them hostage hundreds of miles south of Oman.
The Adams, who were retired, had been sailing full-time on their 58-foot yacht, the Quest, delivering Bibles around the world.
The indictment accuses at least three of the indicted men of shooting and killing the four Americans without provocation.
The men face mandatory life sentences without the possibility of parole if convicted of the piracy charges. They could also face life sentences on the kidnapping charges.
The suspected pirates made their first court appearances Thursday in Norfolk, which last year was the site of the first successful U.S. piracy prosecution in almost 200 years.
A 15th suspected Somali pirate was not charged because he was a juvenile and had a limited role in the hijacking, officials said.
The Associated Press contributed to this report.
