OTTAWA - This year marks a half-century since the grim night John Wendell Holmes was driven to an RCMP interrogation room to be grilled about his homosexuality.

Holmes, gripped by fear, had known for months he was on the RCMP's list of suspected homosexuals working in the Department of External Affairs. The net was now being pulled tight.

Under intense questioning, Holmes acknowledged his sexual orientation but denied ever having been blackmailed by the Russian intelligence service.

No matter. The RCMP reported to a cabinet panel that Holmes' homosexuality was a "character defect" that in itself made him a national security risk. He had to be forced out for the good of Canada.

Holmes, a brilliant diplomat, had many admirers -- including then Prime Minister John Diefenbaker -- but none could save him.

Within weeks, he checked himself into a Woodstock, Ont., hospital with a nervous breakdown, his career in ruins and prospects uncertain for employment outside government.

Holmes was among hundreds of federal civil servants who were targeted in an RCMP homosexual witch hunt that intensified in 1959 and continued through the 1960s, destroying lives, careers and families.

Most victims of the odious gay purge today remain faceless and voiceless, their ordeals unrecorded. But Holmes' tragic story has been recounted in excruciating detail by author Adam Chapnick in a new book, Canada's Voice: The Public Life of John Wendell Holmes (UBC Press).

"It's a horrible thing that happened," Chapnick said in an interview about Holmes' third degree with police that chilly November in 1959.

"Taking place in the middle of the night, not knowing exactly what's coming, not being able to talk to anyone about it. ...

"I think that there were emotional scars that lasted the rest of his life."

Chapnick's prodigious research focuses largely on Holmes' professional life as a scholar and diplomat, whose views on international relations still resonate for a new generation.

But Holmes' personal life, which he guarded closely, necessarily comes under scrutiny to explain the abrupt end of a meteoric rise at External Affairs and an awkward transition to a career in academia. He eventually became president of the Canadian Institute of International Affairs, in Toronto.

Chapnick finds evidence Holmes engaged in a brief tryst with a Russian man while posted as a Canadian diplomat in Moscow in 1947-48. But he suggests the Russian intelligence service never learned of it and was therefore unable to exploit it to their advantage.

Holmes "would never have put his country's security at risk in any way," Chapnick says.

Other Canadians later posted to Moscow were targeted with homosexual traps set by Russian spies, notably ambassador John Watkins, who died of a heart attack near the end of an RCMP interrogation in 1964.

And it was the growing realization among Western Allies in the 1950s that sexual blackmail was increasingly preferred by Moscow that helped trigger the RCMP's gay purge.

A cabinet directive of 1952 cited "character defects" -- such as homosexuality -- as a security risk. The subsequent purge, launched in 1955, continued through the 1960s, eventually ensnaring almost 9,000 people.

The government even developed a so-called "fruit machine," a failed device that purportedly outed homosexuals by measuring biological responses to lewd pictures.

Diefenbaker, long a champion of civil liberties, was uncomfortable with the RCMP campaign but let it continue for years.

Historians and sociologists uncovered more details of the witch hunt after articles in 1992 by The Canadian Press drew public attention to the bleak episode.

But Chapnick's book, drawing on more than 150 interviews, wide archival research and private papers, is unique for meticulously tracing the impact on one of the purge's most highly placed victims.

Holmes, a reserved man, kept quiet on the matter through to his death in 1988. And Chapnick says some sources remain reluctant or unwilling to talk.

One of them is John Starnes, who in 1959 was asked by his boss at External Affairs to drive a terrified Holmes to the interrogation. Starnes, a friend of Holmes who later became head of the RCMP Security Service, left out many details in his memoirs published in 1998.

"I was simply trying to be very careful since John Holmes' family, and especially a female cousin, were very shocked that John was homosexual," Starnes said in an email response to questions.

"And no less upset that his loyalty might be in question."