A 76-year-old American senior citizen, who was jailed in Spain for smuggling 5lbs of cocaine became an unwitting drugs mule after suffering a brain injury, the US said.

Victor Stemberger, from Virginia, is in a Spanish jail a year after flying into the country with cocaine expertly sewn into bubble jackets in a bag.

The US Justice Department has advised Spain it believes Stemberger was duped into acting as a drug mule for a West Africa criminal network.

The family of the former businessman, who suffered a significant brain injury 15 years ago, said he knew nothing about the drugs.

Stemberger was allegedly first reeled into the scam through emails inviting him into a multimillion-dollar business opportunity.

He pitched himself as perfect for the job and boasted of his credentials as ‘an experienced businessman who does what he says he will do, and executes flawlessly, according to plan.’

The US has asked Spain for evidence it’s gathered, according to correspondence obtained by The Associated Press.

A Vietnam veteran with two master’s degrees, Stemberger specialized in corporate executive coaching and prided himself on being a savvy businessman, his son Vic Stemberger said.

But he hasn’t been the same since a 2006 brain aneurysm left him with impairments in judgment and critical thinking.

Last July, he traveled to Brazil on a trip that was to take him to Spain and on to Asia.

His contacts told him officials would be visiting his Sao Paolo hotel room to help transfer gifts into luggage.

Stemberger reassured his son over email the work was legitimate: ‘Gifts referred to in the message are standard protocol for dealing with government officials in this part of the world. No contraband — be sure of that.’

He was arrested the next day after arriving in Madrid.

As his family works to prove his innocence, even Stemberger, who passed his 50th wedding anniversary in jail, has come around to the idea that he was roped into a scam, his son said.

The younger Stemberger said he understands how extraordinary the saga may sound, joking that if every drug dealer used his father’s defense, no one would be in jail.

But, he said, his father was unquestionably duped.

‘There was never any attempt to commit a crime,’ he said.

Federal officials have for years warned about scams that lure elderly Americans or those with diminished mental capacity into becoming drug couriers.

The scams convince them that they’ll receive payouts if they travel or take some other requested action.

The Department of Homeland Security in 2016 said immigration and border authorities had intercepted more than 140 unwitting couriers, some as old as 87, and that over 30 were believed to still be jailed.

‘One of the common characteristics that we find in these scams is that oftentimes the senior is living alone, has lost a spouse and is lonely,’ said Republican Senator Susan Collins.

She chairs the Senate Committee on Aging and helped secure the release of a Maine man jailed in Spain under similar circumstances as Stemberger.

Stemberger, who marks his one-year anniversary in Spanish detention on July 5, faces a trial next month in Madrid.

His son says the only explanation for his father’s actions is that ‘these perpetrators really connected with our dad under the veil of what he thought was a legitimate business opportunity.’

‘With his diminished mental state, he became the perfect victim of a crime syndicate just like this,’ Vic said.

A spokesman for the Madrid judiciary, who agreed to discuss the case only on condition of anonymity, said Stemberger told authorities he had planned to deliver the jackets to United Nations officials in Asia and he didn’t know they contained drugs.