Argo Related: John Sheardown Canadian "hero" in Iran Hostage Crisis - Dies

(CNN) -- John Sheardown, a Canadian immigration officer who helped shelter and smuggle six American diplomats out of Iran in 1980, has died, his son said Monday. He was 88.

Sheardown had Alzheimer's and suffered from colon and prostate cancer, said Robin Sheardown, who described his father as his best friend. John Sheardown died Sunday night at a hospital in Ottawa, Canada.

"He was a very humble man and a real Canadian hero," his son told CNN.

John Sheardown played a key role in what has become known as the "Canadian Caper," a covert operation by the Canadian government and the CIA to rescue six American diplomats who eluded capture during the seizure of the U.S. Embassy in Tehran.

The episode was made famous again this year by the release of the hit movie "Argo," loosely based on the real-life drama. The film, however, left out Sheardown's contributions.

Sheardown was an immigration officer at the Canadian Embassy in Tehran when students and militants stormed the U.S. Embassy there on November 4, 1979, taking more than 50 Americans hostage. Just half a dozen evaded capture.

Sheardown and Ken Taylor, the Canadian ambassador to Iran, hid those six envoys in their homes, protecting them until they could be spirited out of the country with Canadian passports in late January 1980.

"John Sheardown remained a very humble man, always willing to stay in the shadow of others, and the people of Windsor remain extremely proud of his diplomatic intervention and career accomplishments," read a proclamation that declared November 10, 2012, "John Sheardown Day" in the city of Windsor, in Ontario, Canada.

According to that proclamation, Sheardown, a Windsor native, was shot down while serving with the Royal Canadian Air Force during World War II. He worked with his country's customs and immigration department before joining Canada's foreign service, it said.