– For decades, Israel's National Center for Forensic Medicine has tested skeletal remains secreted across its northern border, checking whether the DNA matched that of Israeli soldiers missing behind enemy lines in Lebanon or Syria.

"From time to time they'd bring the samples," said Chen Kugel, the head of the forensics center. "It was always: maybe this time, maybe this time, maybe this time."

There was never a match. Then, this year, that changed. Residents of the camp had grown up hearing rumors that the bodies of missing Israeli soldiers were hidden among the tombstones, but the exact whereabouts were held secret.

Digging began in the cemetery as early as 2013, residents said, and over the years rebel groups and ISIS militants raced to find what would be a highly prized bargaining chip.

Israeli and Syrian forces clashed in June 1982 in Lebanon's Bekaa Valley, and Israeli troops had invaded Lebanon days earlier, targeting the presence of the Palestine Liberation Organization. Staff Sgt. Zachary Baumel, an American Israeli born in Brooklyn, was driving a tank when his unit was attacked by Syrian forces.

The tank was hit, and Baumel and his crew leaped from the burning vehicle and came under fire.

Baumel was declared missing, along with five comrades.

One of the crew, Staff Sgt. Ariel Lieberman, who was captured by Syrian forces, was released in a prisoner exchange two years later. In 1985, two Israeli captives — including Baumel's tank commander Hezi Shai — were released in another exchange. The body of another tank commander was also turned over. Even Baumel's tank was returned.

But there was no sign of Baumel, cannon loader Zvi Feldman and Cpl. Yehuda Katz.

'A race against time'

Palestinians living in the Yarmouk refugee camp on the outskirts of the Syrian capital, Damascus, might have dismissed the rumors of buried Israeli bodies as just that. But about a decade ago, the residents started receiving anonymous calls and text messages, widely believed to be from Israeli intelligence, offering rewards for information.

Residents grew convinced the bodies were in the cemetery, somewhere. "Everyone knew it, everyone," said Thaer al-Sahli, a poet and filmmaker who fled Yarmouk for the Netherlands in 2014.

As Syria slid into civil war in 2011, control of the camp shifted to Syrian rebels and Palestinian groups fighting against Syrian President Bashar Assad's government.

Over the years, the Russian troop presence had been building to reinforce Assad, turning the tide of war against the Syrian rebels. Israeli officials had been watching the shifting dynamics, waiting for a moment when they might be able to retrieve any of their fallen soldiers. Israel, still in a state of war with Syria, then reached out to Moscow.

During negotiations over the surrender and withdrawal of the rebels, the Russians asked these opposition forces last year to retrieve something from the cemetery, said a person with knowledge of the talks. "It was a race against time, a competition between ISIS, which was still looking for these corpses, and the Russians who also wanted to have these corpses," the person said.

Forensic's central role

The dilapidated appearance of the squat, three-story building in Tel Aviv belies its central role in Israel's efforts to recover its war dead. It is the only forensic center in Israel.

The center had previously obtained samples suspected to be from Guy Hever, a soldier who went missing after walking off his base in the Golan Heights in 1997, but they weren't. Nor was there a match for samples thought to belong to Ron Arad, a pilot who went missing in 1986 after ejecting from his airplane during a mission over southern Lebanon.

When the bags from Yarmouk finally arrived, they were opened in a basement room. "One of the bodies was very dramatic," Kugel said. "After cleaning of course, we saw the soles of the shoes with printing in Hebrew. We saw the military overalls, with Hebrew at the back, so we understood it might be someone that we were looking for."

The forensics center compared the remains with a database of DNA from relatives of those missing and found a match. It was Baumel.

When the confirmation came, some of the officers accompanying the body cried, Kugel said. "In Israeli culture it's very important to show that we look after the soldiers and bring them home," he said.

Baumel was finally laid to rest in a military funeral in Jerusalem.