After a yearlong hunt, Sinwar’s killing came down to chance

On Wednesday, Sinwar’s luck ran out. He was killed in a chance encounter with Israeli commanders-in-training on patrol. They had no idea who he was.

The moment that changed the war in Gaza came around 3 p.m. when the trainees searching for Hamas tunnels in the southern city of Rafah saw three armed men leaving a building.

The soldiers opened fire. One of the men fled into a nearby building. Soldiers sent a reconnaissance drone in after him. The video feed showed the militant wounded and alone, sitting in a chair.

In a final act of defiance, the man hurled a chunk of wood at the drone, before the soldiers opened fire again—and the house collapsed on him.

It wasn’t until the next morning, when other soldiers returned to sift through the rubble, that they noticed a resemblance between the dead militant and Sinwar, the Middle East’s most wanted man.

“We operated a lot of fire, a lot of artillery," a soldier involved in Wednesday’s operation, whose name wasn’t disclosed, told Israel’s Channel 12 news. “When we heard he was killed, we joked around saying, ‘How crazy would it be if it was us?’"

Day in and day out since Oct. 7, the deadliest day for Israelis since the founding of their country in 1948, soldiers and spies had searched for Sinwar, using all the technology and advanced weaponry that Israel and its allies, including the U.S., could bring to bear.

At times they came tantalizingly close, but he was always one step ahead. At one point, soldiers arrived in an underground compound just moments after Sinwar had fled, with one senior officer saying Sinwar had left behind a cup of coffee that was still hot.

But they could never catch the man—until members of Israel’s Battalion 450, which trains infantry commanders, stumbled upon him.

Shifting ground

With the death of Sinwar, who devised and led the Oct. 7 attacks, leaving 1,200 people dead and more than 200 held hostage, Israel has now killed nearly all of Hamas’s top leaders in Gaza, with the significant exception of Sinwar’s brother Mohammed.

Mohammed oversees the Iran-backed Islamist group’s day-to-day military operations and could potentially become its leader now.

The killing is a crowning achievement for Israeli Prime Minister Benjamin Netanyahu, who had called for Sinwar’s death as part of his oft-touted goal of “total victory."

The militant leader’s demise also caps an extraordinary three-month run for Israel’s military and intelligence services elsewhere.

In late July, Israel killed Hamas political leader Ismail Haniyeh in Tehran and top Hezbollah commander Fuad Shukr in Beirut. In August, it wounded thousands of Hezbollah members by detonating their pagers and walkie-talkies, eliminated most leaders of the group’s elite Radwan force at a secret meeting and killed leader Hassan Nasrallah in an airstrike in Beirut’s southern suburbs.

U.S. officials are now pushing hard for a cease-fire they hope will lead to a return of the roughly 100 hostages, including many believed to be dead, who remain in Gaza, after most others were released during a cease-fire last November and a handful were rescued.

But for Sinwar’s supporters, the way he died, wearing a combat vest and found with prayer beads and religious books, could burnish his legend as a fighter battling until his last breath.

The video images of Sinwar’s final moments “will only ensure defiance and fighting continues, and show him as a man who stood by his words," an Arab official involved in cease-fire negotiations said.

To the surprise of many Palestinians and Israelis, he was found above ground, rather than hiding in tunnels and surrounded by Israeli hostages, whom Israeli officials have said he used as human shields.

It isn’t clear what he was doing in the run-up to his discovery, but there were no hostages found or civilians killed in Wednesday’s operation, according to Israel.

According to two senior Hamas officials outside Gaza, the group determined it might have lost Sinwar around dawn on Thursday after efforts to reach his companions were unsuccessful.

The group received final confirmation of his death about two hours after images of Sinwar’s dead body started circulating online, when they were contacted by Egyptian and Qatari officials, who were briefed by Israel.

Closing in

Israel for weeks had thought that Sinwar could be in the Tel al-Sultan area of Rafah, the neighborhood where he was killed and a once bustling community that has emptied out since Israeli forces invaded the city, around two kilometers away from Gaza’s border with Egypt.

They based that assessment on intelligence gathered by the Israeli military and Shin Bet, Israel’s internal security service, according to Shalom Ben Hanan, a former senior Shin Bet official briefed on the matter.

Their intelligence included the discovery of Sinwar’s DNA in a tunnel in Tel al-Sultan, a few hundred meters away from where the bodies of six Israeli hostages were found shortly after their execution in August.

Israel’s chief military spokesman, Rear Adm. Daniel Hagari, said that the military believed Sinwar had been on the run, moving from house to house in the area for a long period. Sinwar was probably attempting “to escape to the north, to safer areas" as soldiers closed in, he said.

Still, Hagari said, no one knew exactly where he was.

On Wednesday, members of the Battalion 450 infantry unit—a training battalion that during wartime takes part in fighting—were trying to clear the area of militants and look for tunnels and other Hamas military sites.

Then they spotted the three militants exiting a building that was thought to be empty, according to an Israeli security official. Two of the figures were covered in blankets and appeared to be leading the third man behind them.

After Israeli forces opened fire, the men split up, with Sinwar escaping into a yellow and brown multistory residential building. The Israeli soldiers fired a tank shell at the structure and then sent in a drone.

The video feed from the drone, released later by Israel’s military, showed a badly damaged building littered with dust and debris, exposed wires and scattered furniture. It also showed a man, sitting motionless with his back to the drone, in a chair, with his face covered with a cloth.

The Israeli military said it was Sinwar.

His arm appeared to be wounded. Then suddenly he heaved a piece of wood at the drone, attempting to bring it down, but he failed. The video provided by the military ended at that point.

The battalion commander then gave the order to a tank to fire once more, causing the building to collapse.

The military also fired at a nearby building where the other two militants hid, killing both of them. Israeli authorities haven’t publicly identified them.

At the time, the soldiers had no idea who the three militants were, and decided not to immediately enter the buildings, instead moving on.

Israeli forces returned early the next morning. It was then that they realized one of the deceased militants, wearing a ceramic bullet-protection vest and half-buried beneath debris, looked like Sinwar.

“All of the soldiers walk around with his picture," said Ben Hanan, the former senior Shin Bet official.

The soldiers quickly sent word up the chain of command and also to Shin Bet. Scanning the area, they found 40,000 shekels, or nearly $11,000, in cash and a Palestinian passport of someone other than Sinwar, along with other possessions, including a pack of Mentos.

As the day went on, pictures of a dead body that resembled Sinwar in the wreckage of a building began to surface on social media. How the photos ended up online was unclear, but they put pressure on Israeli authorities to respond.

By Thursday afternoon, the Israeli military put out a statement saying it was working to determine whether one of the bodies was Sinwar. It also notified the U.S. that he likely had been killed.

Despite the clear resemblance, the forensic identification process took many hours. One thing the police’s institute for forensic evidence did was to compare a picture of Sinwar’s teeth to images they had on file from the early 2000s, when he spent several years as an Israeli prisoner.

Photos of the dead man’s mouth, published later by police, showed the same arch-shaped chipped tooth and gap at the center of his top teeth. That was the first confirmation that it was indeed Sinwar.

They then received DNA samples and fingerprints taken from the body. They matched those to fingerprints and DNA records from Israel’s prison system and the Israeli Health Ministry, which provided health services to him when he was in detention.

Finally, just before 8 p.m., the military formally announced Sinwar’s death, followed by a statement by Netanyahu 30 minutes later.

“I am standing here today to announce that Yahya Sinwar was eliminated," Netanyahu said in the short video, standing in front of Israeli flags. But, he said, “The war isn’t over."

Write to Anat Peled at anat.peled@wsj.com, Dov Lieber at dov.lieber@wsj.com and Summer Said at summer.said@wsj.com