The first piracy case to be tried in a U.S. court since the Civil War went to jurors Monday after they heard closing arguments in the prosecution of five Somali defendants accused in an April 1 attack on a Navy ship off the coast of Africa.

The U.S. District Court jury was to begin deliberations Tuesday morning on 14 counts, including a charge of piracy that calls for a mandatory life term.

Jurors heard 4½ hours of closing arguments from the government and attorneys for the five defendants on the assault of the USS Nicholas, a Navy frigate that was patrolling the pirate-infested waters off Somalia when it encountered fire from an 18-foot skiff.

"These defendants do what pirates do," said Prosecutor Joseph E. DePadilla. "These men committed a vicious attack against the men and women of the U.S. Navy. They need to be held accountable."

William Holmes, an attorney for one of the five, pointed to the government's own witness, who he said testified that the men's alleged actions were not completely consistent with pirate attacks off Africa.

"The facts are very different from a typical pirate attack," Holmes said. "They didn't know how pirates attack."

One defense attorney referred to the three accused of attacking the 453-foot, battle-tested Nicholas as "the Marx Brothers" because of their erratic approach.

"Simply being at the wrong place at the wrong time is not a crime," said James E. Short, another defense attorney.

Legal and maritime scholars said the last piracy prosecution to go to trial in the U.S. was in 1861. The trial of the 13 Southern privateers deadlocked. The men were later exchanged with the South.

A piracy prosecution would be the first in the U.S. in nearly 200 years.

The defendants, including three who testified during the nearly two-week trial, attacked the Nicholas after mistaking it for a merchant vessel, the government said. The men raked the Nicholas with fire from AK-47s, and were armed with a rocket-propelled grenade launcher but did not fire it, according to prosecutors. No sailors were injured.

When the Navy returned fire, the Nicholas pursued the skiff and captured two other suspects in a larger vessel.

The men initially told an interpreter they were fishermen, but later acknowledged they were pirates.

Benjamin L. Hatch, another prosecutor, said during his rebuttal that the defense's tack to question aspects of the assault was "just smoke." He said the defense amounted to: "We didn't do it, but if you think we did it, someone made us do it."

The defendants, each wearing oversized suits over their thin frames, listened to the closing arguments through an interpreter. One put his head on the defense table and appeared to nod off as the testimony went into the evening.

Five other Somali defendants are also awaiting trial in Norfolk for a separate attack off Africa. They are accused in the April 10 attack on the USS Ashland. A judge tossed the piracy count in that case, contending the men's actions did not meet the legal definition of piracy.

The government is appealing.