CNN
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Hamas leader Yahya Sinwar, believed to be one of the architects of the militant group’s October 7, 2023 terror attack and Israel’s most wanted man, was killed in Gaza on Wednesday, according to the Israeli army.

Sinwar was one of the main targets of Israel’s war against Hamas in Gaza, and Israeli officials labeled him by many names, including the “face of evil” and “the butcher of Khan Younis.” Previously a very public figure, Sinwar had not been seen since the October 2023 attacks and likely survived the final year of Israel’s siege of Gaza by bunkering down in an extensive network of underground tunnels.

In August, Sinwar became one of Hamas’s top leaders after his predecessor Ismail Haniyeh was assassinated in the Iranian capital Tehran.

But he had long been a key player in the militant group. Sinwar joined Hamas in the late 1980s and quickly rose through the ranks. He founded Hamas’s feared international intelligence agency, the Majd, and was known for his brutal violence against anyone suspected of collaborating with the Israelis. He was also seen by some as a pragmatic political leader: in 2017, Hamas chose Sinwar as the political head of its main decision-making body, the Politburo, in Gaza.

Sinwar was born in 1962 in a refugee camp in Khan Younis, southern Gaza. His family was displaced from the Palestinian village of Al-Majdal – now the Israeli city of Ashkelon – during the Arab-Israeli war.

Sinwar enrolled at the Islamic University in Gaza in the early 1980s, where he studied Arabic, was involved in Palestinian nationalist student organizations and was detained for his participation in anti-occupation activism. In 1985, before Hamas was formed, he helped organize the Majd, a network of Muslim youth that exposed Palestinian informants working with Israel. This group would later be merged into the Hamas security apparatus of the same name.

Sinwar was imprisoned in Israel in 1988 with four life sentences, accused of orchestrating the murders of two Israeli soldiers and four Palestinians suspected of collaborating with Israel.

During his incarceration, Sinwar is said to have abused and manipulated fellow prisoners, punished those considered informants and bullied others into taking hunger strikes.

Sinwar said he spent his years in prison studying his enemy, and learned to read and speak Hebrew through the Open University.

In 2011, he was released as part of a prisoner swap in which more than a thousand Palestinian prisoners were exchanged for Gilad Shalit, an IDF soldier held in Gaza for five years.

At the time, Sinwar called the exchange “one of the great strategic monuments in the history of our cause.” Sinwar’s release is attributed to the fact that his brother was one of Shalit’s kidnappers, who insisted that Sinwar be included in the deal.

After being released, he returned to Gaza, where he began his rise in the militant organization and became infamous for the violent treatment he would mete out to suspected collaborators.

While some viewed Sinwar as a tough militant, others saw him as a master strategist.

Fifteen years after his prison sentence, he used his Hebrew skills to urge the Israeli public to support a ceasefire with Hamas in an interview with an Israeli broadcaster. “We will not recognize Israel, but we are ready to conclude a long-term ceasefire with Israel that will bring peace and prosperity to the region,” he said.

And in a rare interview with an Italian journalist in 2018, Sinwar indicated the group was willing to find a political solution, saying: “A new war is in no one’s interest.”

He also alluded to the realities he and others in Gaza faced during the Israeli blockade, drawing on his own experiences in Israeli prison. “I never got out – I just changed prisons,” he said of life in Gaza.

In 2018, Hamas, led by Sinwar, launched its ‘March of Return’ campaign, in which Gazans protested weekly at the Israeli border, calling on Israel to lift their blockade and give Palestinians the right to return to their ancestral villages and towns. The demonstrations attracted international attention and support from human rights organizations. At one of the protests, Sinwar cheered on those facing “the enemy besieging us.”

As the group’s political leader, Sinwar focused on the group’s foreign relations and forged important ties with regional Arab powers.

He was responsible for mending Hamas’s relationship with Egyptian leaders who were wary of the group’s support for political Islam, and for securing continued military funding from Iran, according to research by the European Council on Foreign Relations (ECFR).

Israel has publicly accused Sinwar of being the “mastermind” behind Hamas’ terror attack on Israel on October 7 – although experts say he is likely one of many – making him one of the main targets of the war in Gaza.

The attack was the deadliest attack in Israel’s history. Hamas and other Palestinian armed groups have killed more than 1,200 people, mostly civilians, and have also taken about 250 people hostage into Gaza.

Sinwar was considered a crucial decision-maker and likely the main point of contact within Gaza during the intense negotiations over the return of the hostages brought to the enclave by Hamas during the October 7 attacks. The talks involved senior figures from Israel, Hamas, the United States, Qatar and Egypt.

During the war, Sinwar consolidated Hamas’s leadership and became by far its most important figure. His influence grew even more after the assassination of other senior Hamas officials, including Mohammed al-Masri, popularly known as Mohammed Deif, the commander of the Al-Qassam Brigades, the military wing of Hamas, and Deif’s deputy, Marwan Issa.

In 2015, Sinwar was designated a global terrorist by the US State Department and the European Union. In recent years he has been sanctioned by Britain and France.