Initially not many believed Igor Gouzenko's claim about there being a spy ring in Canada. Norman Robertson and other Canadian diplomats had to convince Prime Minister Mackenzie King to take this claim seriously and when an investigation was set forth, numerous suspected spies were found and Fred Rose was just one.

Suspected spies were found in the British Royal Commission, in a Canadian scientific lab researching atomic bomb, and various other high level organizations. In fact, the government learned that some of these spies had sent samples of Canadian uranium to the USSR.

It's important to take this with a grain of salt because this was during the Red Scare; fear was heightened and many of the people accused of being spies were not actually spies. For example, five months after Gouzenko's arrival they decided to investigate the Royal Commission. The investigation resulted in twenty arrests and nine were acquitted but spent the rest of their lives in suspicion; a military researcher was detained and questioned for five weeks without charge.

One of the most well known examples of the communist witch hunt in Canada was Herbert Norman, a Canadian diplomat who ended up on a list of suspected communists - both the Canadian and the American governments deemed him with suspicion and while the former eventually determined he was not a threat, the latter continued to label him as a communist throughout the 1950s. Norman committed suicide in 1957.

Another was the case of Gordon Martin, a former member of the Royal Canadian Air Force who went to law school after the war. While applying for the Bar he was questioned about his politics and while he admitted to being a member of the Communist Party, he also strongly believed that this line of questioning went against his freedom of thought. He was rejected from joining the Bar and his family received an apology for this 24 years after his death.

In summary, there were Fred Rose certainly was not the only person considered a spy, not by a long shot. But it's important to remember the context of the investigations that took place; being formally accused of spying - even if found innocent shortly thereafter - had a significant amount of stigma attached to it and lives were ruined because of this.

Source:

Norman Hillmer, Empire to Umpire