Seyed-Emami, a USA -trained scholar, had been managing director of the Persian Wildlife Heritage Foundation, which seeks to protect Iran's rare animals.
"The news of my father's passing is impossible to fathom".
Seyed Emami's son Ramin said in social media posts that prison authorities had informed the family Friday that he had taken his own life.
Kavous Seyed Emami's death was announced Saturday on the of his son, singer Ramin Seyed Emami.
Seyed Emami was one of the founders of the Persian Wildlife Heritage Foundation, an Iran-based environmentalist group. "I still can't believe this", Raam Emami wrote from an unknown location. "Canadian consular officials in Ankara are working to gather additional information and are providing assistance to the family".
"He was one of the defendants in a spying case and unfortunately he committed suicide in prison since he knew that many had made confessions against him and because of his own confessions", Tehran's prosecutor Abbas Jafari-Dolatabadi told the semi-official ILNA news agency.
Harrison met with Seyed-Emami on a number of occasions while he was in Alberta, and said that he, along with his wife and other colleagues, had the opportunity to dine at his house one night. A U.S. State Department spokeswoman said the United States is "aware of reports that a U.S. citizen has been detained in Iran".
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The Iran Sociology Association also questioned the official account of his death.
"The information published about him is not believable, and we expect officials to respond and to provide the public with information concerning his death", the association said in a statement.
Meanwhile Ali Shakourirad, head of the reformist Islamic Union Party, tweeted that the death had "caused a wave of questions and concerns among the public".
Kavous Seyed-Emami, 63, a dual Canadian national, was arrested last month.
Seyed-Emami received his doctorate in sociology from the University of OR in 1991, according to an online alumni listing maintained by the university.
There is now no Canadian embassy in the country and there are no official diplomatic relations between the two nations. A spokeswoman for Global Affairs Canada, which manages Canadian foreign and trade relations, said on Saturday the government was aware of reports of the death of a Canadian citizen in Iran.
Seyed-Emami presented a lecture to Lethbridge students in October, on ethnic identities and nationhood in Iran. Human rights groups say activists in Iran face the risk of arbitrary arrest and harassment by authorities.