Iranian authorities said that 63-year old Kavous Seyed Emami committed suicide, a claim rejected by his family. Seyed Emami had dual Canadian-Iranian nationality, and was one of a group of environmentalists arrested last month and accused of espionage.
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.
Ramin said his father's death "is impossible to fathom." He added: "I still can't believe this."
The Canadian Foreign Ministry told CNN: "We are aware of these reports. Canadian consular officials in Ankara are working to gather additional information and are providing assistance to the family."
Seyed Emami was one of the founders of the Persian Wildlife Heritage Foundation
, an Iran-based environmentalist group.
The Tehran Prosecutor General, Abba Jafari Dolotabadi, has said members of the group were arrested
for gathering classified intelligence in strategic areas under the guise of scientific and environmental work.
Dolotabadi added Sunday: "This person was one of the accused, and as he knew that many statements were made against him and he had confessed himself, he unfortunately committed suicide in prison."
The family says that Seyed Emami will be buried in the village of Ammameh outside Tehran.
His colleagues and friends expressed shock at his arrest and death.
"Dr. Seyed-Emami was never a political activist. His lectures and thoughts were of course in clash with the official ideology and the way of thinking (the) regime would promote," said Ali Reza Eshraghi
, a former student of Seyed Emami.
"Nature was his passion. He would use any occasion to organize and participate in wildlife tours and nature trips across the country," added Eshraghi, who teaches at the University of North Carolina at Chapel Hill.
The Iran Sociological Association, to which Seyed Emami belonged, questioned the government's official version of events.
"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 Sunday.
A senior official with the UN Environment Programme, Gary Lewis, tweeted that Seyed Emami was "a good man who loved #nature and Iran. He was my friend and will be missed."
A leading opposition politician in Iran, Mostafa Tajzadeh, referred to other recent deaths in prisons which he wants investigated and said that President Hassan Rouhani "must do the same until the real reasons of the death of Dr. Sayed Emami is clear to public."
Tajzadeh was himself held at Evin prison in Tehran for seven years.
One opposition figure inside Iran, Ali Shakourirad, said Seyed Emami's death had "created a wave of questions." Shakourirad leads the reformist Islamic Union Party.
"The incomplete and vague information of the Tehran prosecutor added more questions. What is going on in this country?" Shakourirad tweeted.
Human rights groups outside the country have accused Iranian authorities of systematic abuses in prisons. The Center for Human Rights in Iran, which is based in New York, said Seyed Emami's death "stems from the widespread impunity of judicial and security officials who are getting away with murder, time after time."
Seyed Emami was a professor of sociology at Imam Sadeq university in Tehran and earned his doctorate at the University of Oregon. He was still active in the Persian Wildlife Heritage Foundation, whose website describes its work as "public awareness campaigns and projects to protect endangered species in Iran."
Another member of the environmentalist group detained in Iran last month was Morad Tahbaz, who has dual Iranian-US citizenship.
Some analysts see the arrests of the environmentalists as part of a wider confrontation between reformists and conservatives in the Iranian government on a range of economic and social issues, a rift that grew amid widesporead protests at the beginning of January.
In November, an article by the semi-official Tasnim news agency was highly critical of the foundation. It singled out Tahbaz, who is a board member, alleging that he was a big-game hunter who was also involved in "construction ventures in the USA and the Zionist regime, [and is] also known to have been builder and manager of gambling houses."
The Tasnim report also criticized links between the foundation and Massoumeh Ebtekar, a former environment minister and prominent reformer appointed as a vice president by President Rouhani.