The son of a Canadian-Iranian academic and activist who died under mysterious circumstances in an Iranian prison says he’s “grateful” to the Canadian government for trying to help his mother who has been barred from leaving Iran with no explanation.

Mehran Seyed-Emami told CTV News Channel that his mother, Maryam Mombeini, was prevented from boarding a plane in Tehran, Iran and her passport was confiscated when she tried to accompany him and his brother on a flight to Vancouver earlier this month.

Mombeini returned to her home in Tehran while her sons arrived safely in Canada on March 8.

Although Mombeini has dual citizenship, she has not been able to receive consular assistance because Iran doesn’t recognize dual nationals. Her sons have said they believe Iranian authorities are preventing her from leaving the country to intimidate them against speaking about their father’s death.

Kavous Seyed-Emami, an Iranian-Canadian sociology professor and environmental activist, was arrested on Jan. 24 in Tehran on suspicion of espionage. The 63-year-old academic was held in Iran’s notorious Evin Prison for just two weeks before Iranian authorities announced he had killed himself.

The family has publicly questioned the Iranian government’s explanation of his death in addition to the accusations against him.

Mehran said he spoke to his mother on Tuesday morning to send her well wishes on the start of Nowruz, the Iranian New Year. He said she is still reeling from the death of her husband and their separation during the holiday has been difficult for her.

“She’s obviously heartbroken. She’s trying to stay strong because she doesn’t want me and my brother to worry about her, but it’s our immediate concern to get her here as soon as possible,” he said on Tuesday.

Although she has received no word from the Iranian officials about why she was barred from leaving, Mehran said his mother has been comforted by the Canadian government’s vocal support.

On Monday, Foreign Affairs Minister Chrystia Freeland issued a statement calling on the Iranian government to allow Mombeini to return home.

“Canada is gravely concerned that Maryam Mombeini’s travel ban was not lifted over the weekend. We continue to call on Iranian authorities to immediately give Maryam Mombeini, a Canadian citizen, the freedom to return home,” the statement read.

Freeland also said they would continue to demand answers from the Iranians on the circumstances surrounding Seyed-Emami’s death in custody.

Prime Minister Justin Trudeau reiterated the Canadian government’s position in a tweet published later that day.

“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 said his mother appreciates the Canadian government’s involvement and that she was pleased to receive a personal phone call from Freeland herself.

“[That] gave her further comfort and further reassurance that the Canadian government has prioritized this issue. It is on top of their agenda and they’re doing their absolute best to get my mom home,” he said. “We really believe that this is the case.”

Although he doesn’t know if Iranian authorities will listen to the Canadian government’s calls for action, Mehran said he hopes the international attention on his family’s case will pressure the Iranians to provide answers.

“We don’t want a single day to pass where there’s no action happening and nothing is being done to get her home,” he said.

Mehran said his family will probably have to wait two weeks until the holidays in Iran are over before they receive an explanation as to why his mother’s passport was confiscated.