More than three years after federal agents locked up a Sri Lankan immigrant they say was the top U.S. representative of the Tamil Tigers, his fate may hinge on a complex question: Was the rebel group a terrorist threat to Americans?

Federal prosecutors who charged Karunakaran Kandasamy with supporting terrorism say the answer is yes. And they say he should get a stiff sentence approaching 20 years for raising money for the separatist group, which fought a 25-year war with the Sri Lankan government.

But a judge recently expressed his doubts.

The case against the jailed Kandasamy doesn't neatly fit the definition of "a more obvious or garden variety terrorism case, where ... our security interests are compromised and the safety of our citizenry is in jeopardy," U.S. District Judge Raymond Dearie said earlier this month at Kandasamy's scheduled sentencing, which was postponed.

"Do we simply wave the red flag of terrorism and impose the maximum sentence?"

Assistant U.S. Attorney Jeffrey Knox argued the Tamil Tigers had earned a State Department designation as a terrorist organization in part by putting U.S. citizens living in Sri Lanka in harm's way. He also said the group's supporters in the United States extorted cash from Sri Lankan immigrants.

The Tamil Tigers pioneered and perfected technology for suicide bombings, Knox said. That technology "was borrowed and copied and sold on some occasions to other terrorist organizations — organizations like al-Qaida, that directly target the United States, organizations like Hamas and Hezbollah and other in the region," he said.

Internal documents show the Tamil Tigers considered other terror groups as fellow freedom fighters, and had a policy of "sharing black market arms shipments and explosive shipments, the financial system, bank accounts," he said.

The judge put off sentencing after Kandasamy — who has battled a spinal problem and other serious ailments since his arrest — asked for mercy.

"I love this country and its soil," the 54-year-old former cab driver said through an interpreter. "I'm sick and I'm afraid I'll never live to be free with my family again."

No new sentencing date was set. A spokesman for the U.S. Attorney's office in Brooklyn declined to comment on Friday.

Kandasamy's case has inched forward as events his native country took a historic turn.

Last year, the Tamil Tigers admitted defeat in their 25-year war with the Sri Lankan government. The clash killed more than 70,000 people, including reclusive rebel leader Velupillai Prabhakaran.

The rebels, who once controlled a de facto state in the island nation's north, had been fighting since 1983 for a separate state for minority Tamils after decades of oppression by the Sinhalese majority. Responsible for hundreds of suicide attacks — including the 1991 assassination of former Indian Prime Minister Rajiv Gandhi — the Tamil Tigers were shunned internationally and branded terrorists by the U.S., European Union and India.

Federal authorities in New York had sought to cut off support for the group by arresting sympathizers in their East Coast immigrant communities in 2006 and 2007 on charges of conspiring to provide material aid to a terrorist organization.

Some were accused of helping to buy explosives, missiles, anti-aircraft guns and other weapons, and with trying to bribe U.S. officials to remove the group from the terrorism list. Others, including Kandasamy, were tied to a covert campaign to raise and launder millions of dollars through a charity front organization.

Kandasamy and other defendants have pleaded guilty to terrorism charges, with some receiving sentences of 25 years.

Defense attorney Charles Ross has argued that his client's punishment should be less than five years. A 20-year term, he said, would be "an almost knee-jerk maximum sentence" that ignores the complexities of Sri Lanka's civil strife.

At the recent hearing, Kandasamy told the judge he fled Sri Lanka "because the Sinhalese were killing my people and I was afraid got my life and the lives of my family."

Once Kandasamy received political asylum, his lawyer said, his main goal was to make enough money to start bringing his loved ones to the United States. He also raised money for a Tamil charity, focusing on humanitarian causes.

"He was not primarily concerned with arming a terrorist organization," Ross said. "He was primarily concerned, your honor, with helping his people."

Prosecutors counter that Kandasamy and others were well aware that their fundraising was fueling violence. They say there's evidence that he helped raise millions of dollars for the Tamil Tigers, and that he went to Sri Lanka to meet with rebel commanders.

"There are two sides to this war, no question about it," Knox said. "But (Kandasamy) is not blameless."