Abdul-Hamid Al-Youssef recounts how he lost 25 members of his family, including his wife and twins when their town in Syria was attacked with poisonous gas in 2017, an attack that a UN-backed investigation concluded was carried out by the Syrian regime.
Al-Youssef, 33, said: "In seconds, everything was wiped out. Life was completely wiped out," after the sarin gas attack in the town of Khan Sheikhoun.
The attack was one of dozens in which chemical weapons were allegedly used during the country's 11-year war.
The New York-based Human Rights Watch said that the bombing in northwest Syria, which is under the control of the opposition, killed at least 90 people, including 30 children.
Meanwhile, Russia and China, allies of the Syrian regime, used their veto power to block UN efforts to open an investigation into war crimes and crimes against humanity in Syria at the International Criminal Court (ICC).
On the five-year anniversary of the Khan Sheikhoun attack, survivors and human rights activists warn that not being held accountable for the chemical attacks in Syria could encourage the regime to commit them again.
Al-Youssef demands that the head of the Syrian regime, Bashar Al-Assad, be held accountable, saying: "Despite the presentation of witnesses, despite the presentation of evidence, and despite all evidence being delivered to the UN and to the concerned authorities, to this day there has been no accountability for Bashar Al-Assad."
Al-Assad's government denies using chemical weapons in the war, which began as an uprising against his rule before turning into a war in which at least 350,000 people were killed. In 2013, Syria signed international treaties banning the use of such weapons.