US aircraft carrier strike group arrives in Middle East

After dedicating his life to fighting the Assad regime, Mazen Al-Hamada did not live to see it fall.

A symbol of resilience and courage, the famous Syrian activist was found dead in the "slaughterhouse" prison of Saydnaya in Damascus, where he had been held since he returned to Syria in February 2020.

An unverified photo circulating online shows his disfigured face and suggests he was killed just before the rebels reached the prison, according to independent observers.

Al-Hamada was first arrested in 2011, when he protested against the regime, and remained in prison for two years. He left Syria in 2013 and was granted asylum in the Netherlands a year later.

That's when the world got to know the horrors he endured, which he bravely described as he spoke to huge crowds, policymakers and the press, voicing the struggle of thousands who like him were detained by Assad's regime -- at least 157,000 between 2011 and August 2024, according to a report by the Syrian Network for Human Rights.

“I will not rest until I take them to court and get justice,” Al-Hamada said in an interview for a 2017 documentary, ‘Syria's Disappeared,’ his sunken eyes in tears unable to hide the pain behind his words. “Justice for me and my friends who they killed. Even if it costs my life. Bring them to justice, no matter what."

-ABC News' Camilla Alcini

The White Helmets said they have searched a second prison in Damascus within a training center for the Assad regime's State Security Branch.

"Our teams conducted searches and inspections inside the prison and the basement, which contains collective and solitary confinement cells, where innocent people were detained and brutally tortured. The teams found papers with numbers of soldiers who worked in the branch. The teams contacted them and they confirmed that the cells were only within the basement and that there were no hidden detention centers in the place," the White Helmets said in a statement.

After searching Monday for secret prisons and cells, the White Helmets are now demanding Bashar Assad hand over the locations of the regime's secret prisons along with a list of detainees being held.

Many believe there are still prisons that have yet to be discovered.

"The defunct Assad regime has practiced indescribable brutality and criminality in killing, arresting, and torturing Syrians, prolonging the period of oppression and pain in the hearts of mothers. Justice for all victims and holding accountable the perpetrators of crimes against Syrians is the first step in healing wounds and supporting peace-building efforts," the White Helmets said in a statement Tuesday.

The White Helmets said they sent a request to the United Nations through an international mediator to demand that Russia pressure Assad to release the information so the prisoners can be reached.

Israel will act decisively against positions in Syria if Hezbollah reemerges, but it has "no intention of interfering in the internal affairs of Syria," Prime Minister Benjamin Netanyahu said in remarks Tuesday.

"I authorized the Air Force to bomb strategic military capabilities left behind by the Syrian army, so that they would not fall into the hands of the jihadists," Netanyahu said.

"We want relations with the new regime in Syria. But if this regime allows Iran to re-establish itself in Syria, or allows the transfer of Iranian weapons or any other weapons to Hezbollah, or attacks us -- we will respond forcefully and we will exact a heavy price from him," Netanyahu said.