VANCOUVER -- Almost two months since an Iranian-Canadian professor died in a Tehran prison, his sons still haven't had a moment to grieve.

Mehran Seyed-Emami says it's too important to get his mother Maryam Mombeini safely to Canada and out of Iran to focus on anything else.

Her sons say Iranian authorities blocked Mombeini from boarding a Vancouver-bound plane with her sons in Tehran two weeks ago and confiscated her passport.

"The longer we wait, the higher the risk of something potentially happening to her," he said in an interview.

"Me and my brother are trying to stay strong, trying to get my mom home as soon as possible. And then, we can grieve together."

He said he's grateful for the Canadian government's efforts to secure her release. Foreign Affairs Minister Chrystia Freeland has spoken with Mombeini directly twice, he said.

But he also understands its capacity is limited, since Canada does not have an embassy in Iran and must depend on allies like Italy to act as diplomatic conduits.

On Monday, : "Iran must allow Maryam Mombeini to leave the country and travel to Canada to be with her family -- and the regime must provide answers in the death of her husband, Kavous Seyed-Emami, in Evin prison."

Mehran Seyed-Emami described his father as a calm and balanced man, who taught sociology at Imam Sadeq University in Tehran for 27 years, before he was arrested on Jan. 24 and sent to the country's notorious Evin prison.

He believes it was his father's work as managing director of the Persian Wildlife Heritage Foundation that made him a potential target. The foundation largely worked to protect the endangered Asiatic cheetah, an animal Mehran Seyed-Emami described as a symbol of hope and strength for the Iranian people. The organization had support from the United Nations and other international organizations, he said.

In February, Tehran prosecutor Abbas Jafari Dolatabadi said authorities had arrested several unidentified people on suspicion of spying under the cover of scientific and environmental projects.

"There's a term: You're afraid of what you don't understand. And I think this was one of those cases, because they were doing highly academic and scientific work. ... They thought if someone form the UN or an international organization comes (to Iran), they must be spies," Mehran Seyed-Emami said.

The family's home was raided by dozens of people, who packed 10 suitcases worth of their belonging, including photo albums and the deed to the home, he said.

After two weeks of silence from the authorities, Mombeini was summoned to the prosecutor's office on the pretense that she could see her husband and it would help his case. Instead, she was interrogated for four hours, before being shown her husband's body, Mehran Seyed-Emami said.

Iranian authorities have said Kavous Seyed-Emami's death was a suicide, but the family and others have questioned that finding.

"This is the kind of cruelty we've been dealing with, the kind of trauma that can scar you for life," the son said.

Mombeini and her sons planned to start a new life in Vancouver, where they had lived for eight years after getting Canadian citizenship in 1998. She insisted her sons go without her when she was blocked at the gate.

Since then, the brothers have remained in regular contact with their mother via digital chat apps, Mehran Seyed-Emami said.

"Our home is probably bugged and there are probably microphones in our house, but we don't mind. Even when minister Freeland called, we put it on speakerphone. We want them to hear this, we want them to know the whole world is watching, the whole world is listening," he said.

Tuesday, which marked the Persian Norwuz celebration, was bittersweet for the family. They chatted digitally, with Mombeini in Iran, Mehran Seyed-Emami in Vancouver and his brother Ramin Seyed-Emami in New York.

But Mehran Seyed-Emami said they are motivated by the promise of being together once again.

"It's the opposite of what any of us would have expected or anticipated if you'd asked us a couple of months ago. We're in this chaotic predicament, which no one could have expected," he said.

"Yet we have a sense of responsibility and duty -- not just for us, not just for our family, but perhaps for other families to hopefully prevent these kinds of things from happening."