CAIRO >> The youngest son of the late former Egyptian president Mohamed Morsi has died of a heart attack he suffered while driving in Cairo, doctors said.

Abdullah Morsi, 25, was with a friend Wednesday when he suddenly felt weak. He died shortly after arriving at a hospital in the capital, physicians said on condition of anonymity because they were not authorized to brief journalists.

Mohamed Morsi, whose divisive year in power ended with a military ouster in 2013 following mass protests against his rule, had been in detention since he was toppled. In June, he collapsed and died in court during trial on espionage charges. His death brought criticism from local and international rights groups who accused the government of deliberately denying medical care to political prisoners.

Last year, Abdullah was detained briefly for allegedly spreading false news and belonging to the outlawed Muslim Brotherhood, the islamist group in which his father had held a leadership position. In the same year, his older brother Osama, was sentenced to 10 years in prison in a mass trial that rights group Amnesty International decried as a “mockery of justice.” He and the other defendants were convicted of allegedly inciting violence at a pro-Morsi sit-in that police stormed, killing hundreds of protesters.

Gamal Heshmat, a Brotherhood leader who lives in Turkey, said in an interview with al-Jazeera Mubashir news channel that he hoped Abdullah’s death “would wake people up and attract their attention to the situation of the youths who die every day either morally or physically” in Egyptian prisons.

“Egypt itself has turned into a prison,” Heshmat told the Qatar-funded broadcaster, known for its support of the Muslim Brotherhood, which the Egyptian government has labeled a terrorist organization.

Last year, in a rare interview, Abdullah told The Associated Press that the family had been campaigning to improve his father’s prison conditions, complaining he was denied the right to prison visits. “We want him to be able to have a life — visits and medical care, and eventually freedom,” Abdullah said then.

During his year in office, Morsi was accused of using his electoral victories to further the Muslim Brotherhood’s islamist political agenda. Morsi cracked down at times on protesters and used executive powers to force policies, but never managed to control the levers of power, facing opposition in the courts and among police. In the end, his opponents organized mass demonstrations against his rule, and it was against this backdrop that the military overthrew him.

Since then, the government has largely crushed the organization in Egypt in a ruthless crackdown. Tens of thousands of Egyptians have been arrested since 2013, and many had fled the country.

Abdullah’s sudden death shocked many Muslim Brotherhood members living in exile, who seized the opportunity to express their disenchantment with the rule of President Abdel-Fattah El-Sissi.