Protests have broken out in Iran after a young woman died following her detention by morality police.
Mahsa Amini fell into a coma while in custody in Tehran after being arrested by officers enforcing the country's strict hijab rules.
Police said the 22-year-old was taken to hospital after she allegedly had a heart attack.
Pro-reform news websites quoted an uncle of Ms Amini as saying she had no history of heart disease.
Iran's President Ebrahim Raisi has asked for the cause of the incident to be investigated with "urgency and special attention", state media has reported.
The Center for Human Rights in Iran said Ms Amini had been visiting her family in the capital when she was arrested on Tuesday for her "alleged inappropriate hijab".
"Her family was told that she was being taken for 're-education' and would be released later that night," the organisation said.
Officers apparently found fault with her hijab, or headscarf, according to reports on social media.
The headscarf has been compulsory for women in Iran since after the 1979 Islamic Revolution and members of the morality police enforce the strict dress code.
Over the past few months, Iranian rights activists have urged women to publicly remove their veils in an act of defiance. The gesture can lead to women being arrested for defying the Islamic dress code.
Following her death, social media posts showed protesters chanting "death to the dictator (Khamenei)" as drivers sounded their car horns in a Tehran square close to the hospital she died in.
On Friday, police said there was no violence towards or physical contact between officers and Ms Amini while she was in custody.
Police also shared CCTV footage appearing to show Ms Amini inside a police station, with other detainees.
At one point she stands up from a chair, goes to speak to another woman, then holds her head with both hands, stumbles against a chair and collapses.
In another clip, she is seen being carried away on a stretcher.
'Our children are dying'
Ms Amini's death has drawn condemnation from Iranian celebrities, athletes and other public figures.
Former pro-reform president Mohammad Khatami said the behaviour of the morality police was a "disaster" while US special envoy for Iran, Robert Malley, described the incident as "appalling".
"Those responsible for her death should be held accountable," he added.
Popular ex-football player, Ali Karimi, tweeted that while children of high-ranking officials are leaving the country, "our children are dying".
This is not the first time the country's morality police has been criticised.
In recent years, it has been condemned over its treatment of people, particularly young women, with videos online showing officers forcing women into police vehicles.
Iran's supreme leader, Ayatollah Ali Khamenei, has supported a softer attitude towards women who do not comply with the official dress code.
But hardliners have called for harsh punishment and even lashes, arguing that allowing women to show their hair leads to moral decay and the disintegration of families.
Since 2017, after dozens of women publicly took off their headscarves in a wave of protests, the authorities adopted tougher measures.