South Korean prosecutors said Friday they have discovered that some of the five Somali pirates arrested for the hijacking of South Korean freighter in the Arabian Sea last month had participated in the kidnapping of its sister ship last year, which was released after a huge ransom was paid.

The five Somali pirates were captured in the South Korean naval commando's Jan. 21 operation to rescue the 11,500-ton chemical carrier, the Samho Jewelry, and have been investigated by the prosecution's special team in the southern port city of Busan. The naval operation killed eight other pirates and saved all 21 crew

members, though the South Korean captain, Seok Hae-kyun, sustained several gunshots during the pre-dawn gun battle with the pirates.

Wrapping up an 18-day probe, the Busan Prosecutors' Office on Friday pressed six charges, including maritime robbery and attempted murder, against the five pirates.

"We have discovered that some of the pirates in the Samho Jewelry case were also involved in the kidnapping of the Samho Dream," Jeong Jeom-shik, the special team's chief investigator, told reporters at a briefing.

Two dozen crew members of the Samho Dream were released last November from seven months of captivity in Somalia after its owner, the Busan-based Samho Shipping, reportedly handed over more than US$9 million in ransom.

When the Samho Dream's crew members were asked to identify the captive pirates under detention here, some of them told investigators that they saw the faces of four or five Somali pirates while they were being taken hostage last year, Jeong said.

Prosecutors said that have secured three bullets removed from the injured skipper's body and two of them turned out to be stray bullets fired by South Korea's Cheonghae Unit during the pre-dawn raid.   

According to prosecutors, the third bullet was fired from an AK-rifle, used by one of the pirates, while a fourth bullet, also removed from Seok's body, was lost in Oman along with belongings of a Korean hospital staff member.

Given the position of the bullet from the AK-rifle that penetrated the captain's abdomen, investigators pointed to it as the main factor that thrust Seok into critical condition, adding that the stray bullets were stuck in his side and right knee, respectively.

An earlier probe by police had concluded that only one was a stray bullet and another was a ship fragment from the crossfire on the ship.

Investigators suspect that 23-year-old pirate Arai Mahomed shot Captain Seok at point-blank range, but he still denies this allegation.

Under South Korean law, the pirates could be sentenced to at least five years in prison for hijacking the ship and life imprisonment or even death for firing at the captain from a close distance.

Regarding who was behind the piracy, the African pirates confessed to prosecutors that they have supporters who provide financial assistance, equipment and food as well as a ship owner and a kidnapping negotiator, officials said.

They noted, however, that it was hard to name the specific figures behind the crime as both the pirates' captain and vice leader were shot to death during the operation. (Yonhap News)