A jail inmate told investigators that a suspect in the killings of four people aboard a charter fishing boat admitted his role in their shooting deaths, but insisted he did not pull the trigger, according to court documents.

The inmate, identified only as CS1 in court papers, said Guillermo Zarabozo told him in a jailhouse conversation that co-defendant Kirby Logan Archer fatally shot the captain of the 47-foot "Joe Cool" along with the captain's wife and two crew members in September.

The four people were killed because they refused to take the men to Cuba instead of the originally agreed-upon destination of Bimini, Bahamas, the informant said Zarabozo told him. Zarabozo also supposedly said he threw the bodies into the ocean and cleaned up the boat.

Zarabozo, 20, and Archer, 36, could face the death penalty if convicted of federal charges including murder, kidnapping and seizing control of a ship by force. They have pleaded not guilty and have claimed that the four people were killed by Cuban pirates who attacked the boat at sea.

Missing and presumed dead are the boat's captain, Jake Branam, 27; wife Kelley Branam, 30; his half brother Scott Gamble, 30; and crew member Samuel Kairy, 27. All lived in Miami Beach.

A document summarizing the informant's statements filed by federal prosecutors was ordered unsealed Wednesday by U.S. District Judge Paul Huck.

The inmate told investigators that he was housed in a cell next to Zarabozo at the Federal Detention Center in downtown Miami and that Zarabozo supposedly made the admissions in conversations between the two.

"We are looking into the government's allegations and will respond appropriately in court or in our pleadings," said Anthony Natale, an assistant federal public defender representing Zarabozo.

According to the inmate, Archer, a robbery fugitive from Arkansas, wanted to go to Cuba because the communist nation has no extradition treaty with the U.S. The two paid $4,000 to charter the "Joe Cool" to take them to Bimini on Sept. 22 and then tried to force Branam to head south toward Cuba.

The inmate said an argument followed and Archer pulled a handgun from Zarabozo's luggage and pointed it at Branam, leading Mrs. Branam to tell other crew members to call the Coast Guard.

"Archer then shot the driver, the woman and the remaining crew members," the court filing said. "(Zarabozo) then agreed to throw the bodies overboard because the crew members were shot with his firearm."

Archer then tried to pilot the vessel toward Cuba himself but had difficulty, later becoming "angered and frustrated" because he could find only one shell casing from the weapon, the document said. Investigators have said they found four 9mm bullet casings on the boat similar to ammunition discovered at Zarabozo's home in Hialeah.

The two men eventually decided to abandon the boat and try to reach Cuba on a life raft. Zarabozo told the inmate that "they threw their guns into the ocean."

The Coast Guard rescued the pair from the life raft and found the "Joe Cool" adrift about 30 miles north of Cuba.

Archer is also charged with stealing more than $92,000 from a Wal-Mart in Arkansas, where he had been a manager. His defense attorney in Miami did not immediately respond Thursday to an e-mail message seeking comment on the informant's statements.