South Korea's coastguard plans to wrap up within days their investigation of five Somali pirates captured in a raid on a hijacked freighter in the Arabian Sea in January, an official said on Saturday.
The five Somalis, aged from 19 to 25, were airlifted to the Southern city of Busan on January, 30 to face a criminal inquiry and possible trial.
"We plan to announce the investigation results on Monday and hand the case over to prosecution authorities for indictment," a Korea Coast Guard spokesman told AFP.
"Questioning is currently focused on finding out who shot the captain," he said.
Seok Hae-Kyun, 58, the captain of the Samho Jewelry, is in critical but stable condition after suffering serious gunshot wounds as South Korean navy commandos stormed his 11,500-ton vessel in January, six days after it was hijacked.
Some of the South Korean chemical carrier's crew pointed the finger at a 23-year-old pirate identified as Arai Mahomed, but he flatly denied responsibility, the coastguard said.
The five could face life in prison if convicted of shooting Seok. If he were to die, they could theoretically be sentenced to death, although the country has carried out no executions since 1997.
Piracy has surged in 2011 off Somalia, a lawless, war-torn country that sits astride one of the world's most important shipping routes.
But many of those caught by an international fleet of warships patrolling the area are freed because there is nowhere to try them.
Germany and Spain have recently taken steps to try suspected pirates in their own courts.