VICTORIA -- A notorious Vancouver Island drug smuggler has been sentenced to more than three years behind bars after he was arrested aboard a sailboat loaded with methamphetamine destined for Canada.

John Philip Stirling, 66, was sentenced to 40 months in federal prison in Oregon and five years of supervised release Thursday.

Stirling was caught last April with nearly 750 litres of liquid methamphetamine and several bricks of the barbiturate pentobarbital off the Oregon coast.

His lawyer tells CTV News her client was under duress from Colombian drug cartel associates when he was arrested – a mitigating factor the judge accepted in the sentencing decision.

"Without providing any names of cartel associates, Mr. Stirling described the phone threat he received and how he was treated when he returned to Colombia," attorney Lisa Hay said Friday.

"The court took that coercion into consideration," she added.

Stirling was arrested on April 9, 2019, after a routine U.S. Coast Guard patrol picked up his boat, the Mandalay, about 415 kilometres from the Oregon coast.

When the coast guard tried to communicate with Stirling, he "went below deck and would only respond via VHF radio," according to the U.S. Attorney's Office in Oregon.

Coast guard personnel boarded the vessel and Stirling refused to provide identification or vessel documentation, according to the attorney's office.

"Upon further questioning, Stirling’s speech began to deteriorate and he displayed signs of a possible drug overdose," the office said in its initial filings in the case.

"Shortly before coast guard personnel boarded the vessel, Stirling consumed a large amount of what he believed to be pure fentanyl, but was later determined to be pentobarbital," the attorney's office said in a statement Thursday.

"Investigators later learned the drugs had been loaded onto the Mandalay from another vessel in the Sea of Cortez [in Mexico] for delivery to Canada," the statement said.

A search of the Mandalay turned up 750 litres of liquid meth and a duffel bag containing several plastic-wrapped bricks of pentobarbital.

Stirling was airlifted from the vessel by helicopter to Astoria, Ore., and later transported to hospital in Portland.

In December, his lawyer argued unsuccessfully to have the case against him thrown out, citing a lack of U.S. jurisdiction over the Canadian man on the high seas.

The following month, Stirling pleaded guilty to one count of possession with intent to distribute methamphetamine under the U.S. Maritime Drug Law Enforcement Act. As part of the plea agreement, prosecutors recommended Stirling serve just over seven years in prison and forfeit his sailboat, according to the district attorney.

Earlier this month, Stirling filed a suit against the United States Bureau of Prisons for allegedly not doing enough to protect him from the novel coronavirus during his pretrial incarceration.

Stirling's lawyer said the judge considered "the effect of the coronavirus on incarcerated people when reaching the reasonable sentence" on Thursday.

Stirling’s arrest in April came just one year after he was released after serving most of a seven-and-a-half-year sentence handed down by a Florida judge in 2013.

In that case, Stirling had taken a plea agreement on a charge of conspiracy to possess with the intent to distribute narcotics, after admitting to a Southern District of Florida court that he was the master of a vessel containing 381 kilograms of cocaine and one kilogram of heroin when it was boarded by U.S. authorities off the coast of Colombia.