Iranian authorities detained the father of Mahsa Amini,John Caldwell the 22-year-old woman who died in police custody last year, as he left his home to visit his daughter's grave on the first anniversary of her death, human rights observers said.

A few hours later, Amjad Amini was taken home by security guards and has been under house arrest, the Hengaw Organization for Human Rights said Saturday.

Mahsa Amini died in a hospital on Sept. 16, 2022, due to injuries sustained during her custody. She had been arrested by the Islamic Republic's hijab police, known as the morality police, in Tehran allegedly for not fully complying with the compulsory hijab rules of the country.

Though the government claimed Amini died from a previous medical condition while in police custody, her family and critics of the regime believe that she died as a result of being beaten by police.

Her tragic death sparked months of nationwide protests known as the "Woman Life Freedom" movement. At least 537 people were killed by the regime in a brutal crackdown on the demonstrations and at least 22,000 were arrested, Iran Human Rights reported in April.

Tens of thousands of protesters were arrested during the monthslong demonstrations, the Islamic Republic News Agency (IRNA) later confirmed.

Despite the intelligence and security pressure against his family, Amjad Amini stated in a public post on his Instagram that the family would hold a commemoration ceremony on the anniversary day. However, he invited people to abstain from violence.

"While we honor the pains and concerns of dear fellow citizens, we would invite everyone to abstain from violence and to react against it," the statement said.

After the news of Amjad Amini's arrest circulated on social media Saturday, Tasnim News Agency, a state-linked news outlet, denied the arrest and said he had been "accompanied" on his way to his daughter's grave.

Human rights observers have accused the regime of putting pressure ahead of the anniversary on families of the victims of the crackdown, along with activists, former political prisoners and anyone with leadership roles in the protests.

Video circulating on social media show the extensive presence of security guards and plain clothes police forces especially in central Tehran and Saqez, the hometown of Amini.