Families of Israeli hostages held by Hamas cling to digital clues

TEL AVIV - At 8:30 a.m. on Oct. 7, Hadas Kalderon received the last message from her son.

“Mom, be quiet, don’t move,” Erez, 12, texted. Hamas militants had stormed his father’s house, in their southern Israeli kibbutz of Nir Oz, where he and his 16-year-old sister, Sahar, had spent the night.

Erez and his sister had jumped out the window and were hiding in the bushes. But he was thinking of his mother, just down the road, trying to protect her. Gunmen were rampaging through their tiny pastoral community, shooting entire families, some at point-blank range, as they clung to each other in beds and safe rooms.

“I love you forever. I hope you survive,” she texted back. There was no reply.

For hours, Hadas called Erez’s cellphone again and again, even as she fought for her life, physically blocking militants from breaking down her safe room door. She heard them screaming, “Allahu akbar” as they set fire to parts of her home.

When Israeli forces finally arrived in the late afternoon, the Kalderon family emerged from hiding, and Hadas’s older daughter found an 18-second video circulating on social media. It showed Erez in a black T-shirt, being gripped by both arms and led into captivity. The militants referred to Erez and another group of children who do not appear in the shot as “child settlers.”

Kalderon has replaced eating and sleeping with chain-smoking. Her voice is raw from overuse. She is in a “living hell,” she said, having told her children for years not to be afraid. Now, “the nightmare has come true.”

Five members of the family were taken, including Erez, Sahar and their 50-year-old father, Ofer; their 80-year-old grandmother, Carmela, and a 12-year-old cousin, Noya, were grabbed from another house in the community. There are 203 people being held hostage in Gaza, according to the Israeli government, including civilians with passports from at least 31 other countries.

Hadas’s childhood friend from Nir Oz, whose relatives are also being held in Gaza, has commandeered her cellphone, shielding her from the relentless, looping horrors on social media — the celebrations of the bloodshed, the parading of humiliated captives, some stripped down to their underwear, others huddled together in what could be Hamas’s vast network of tunnels. In one case, militants uploaded a video showing the killing of an elderly woman to her own Facebook page. Her granddaughter discovered it.

The militants’ decision to film their reign of terror has deepened the anguish of Israelis, but it has also given experts in Israel’s vaunted cybersecurity and intelligence sectors a great deal of evidence to work with. They are leading a grass-roots effort now to comb through the footage and the photographs for clues about where hostages are being held.

“The state has the tools and the information, but they don’t have the apparatus to work as quickly as we do,” said Ido Har-Tuv, a former member of Shin Bet, Israel’s secretive national security service, and the chief executive of Gitam BBDO — an advertising agency that has opened a makeshift “war room” out of its offices in a gleaming high-rise in the Tel Aviv suburb of Ramat Hahayal, Israel’s Silicon Valley.

“We’re running our operation here like a lean, efficient start-up,” Har-Tuv said. “We don’t have time.”

Many of the roughly 100 men and women in the “war room” have deep military and intelligence experience, and some are being called up by Israel’s most elite units. They include 8200, the Israeli military’s cyberintelligence division, and Duvdevan, its undercover counterterrorism unit, which was the basis for the Netflix series “Fauda.”

Refael Franco, the former deputy head of the National Cyber Directorate, is overseeing the construction of the group’s platform, which is based on cutting-edge AI and facial recognition technology. It is a sophisticated system that cross-checks images posted by militants posted on social media against photos of the hostages provided by families. When a match occurs, the system can geolocate — within seconds — the approximate location of a missing person. Open-source intelligence experts then try to zero in further, relying on contextual clues like mosques, local shops or the angle of the sun.

The teams have already built a database of an estimated 1,000 people, including hostages and hostage takers. They are getting personnel and logistical help from Google, which has offices across town. They have shared their platform with Israeli security officials, who will use it to further their own search.

But it is a time-consuming and inexact process. One of the biggest challenges, Franco said, is that hostages have been moved repeatedly.

“That being said, every time someone picks up their phone and uploads footage in the strip, we can cross-check it in the system to know where they are,” he said. They will keep following the digital clues, he said, for “as long as this mission takes.”

Most of the videos were filmed and posted during or shortly after the initial abductions, flooding social media sites such as Telegram, Facebook, Snapchat and X, formerly known as Twitter — oftentimes all at once. Many were easy to find because they were posted with the same set of hashtags. In rare instances, Palestinian gunmen could be heard discussing where to take their captives.

One set of videos, believed to be filmed by militants and passersby in the southern Gazan city of Khan Younis, showed a hostage being led by gunmen; on a wall in the background was a phone number of a local businessman, tipping off the team to the neighborhood.

“We’re figuring all of this out as we go,” said one volunteer, among a group hunched over their laptops as they toggled through spreadsheets filled with translated posts, hashtags and geolocations.

The man spoke on the condition of anonymity because he is a reservist with Duvdevan. As time goes on, he said, the militants are posting less and, when they do, they are focusing more on themselves and their injuries.

And as Israel expands its punishing air campaign in Gaza, which has killed more than 3,700 people, hostage takers may lose electricity or cell reception and go dark entirely.

Kalderon has not turned on the news since the attack. All she knows is that 80 of her 400 neighbors are dead or missing. At least 1,400 people in Israel have been killed.

She was unaware of the grass-roots efforts to locate the hostages, but she was not surprised. Across Israel, civilians have mobilized to provide aid to victims in the south and equipment to the troops, filling gaps left by the government.

For a week and a half, Kalderon and her relatives heard nothing from Israeli officials about the status of their loved ones, or efforts to bring them home.

On Wednesday, a military notification officer told Kalderon that her mother, Carmela — a peacenik immigrant from New York who for years helped Gazans receive medical treatment in Israel — and her autistic niece Noya — who was sleeping over at her grandmother’s — were both dead. There was no information about the others.

Kalderon and other relatives of hostages say have they experienced a double trauma: first left to fend for themselves when militants overran their communities, now left to navigate a deafening silence from their government.

“Every second, every second, that our children are there is one second too much, and yet all Netanyahu talks about is ‘winning the war,’” said Kalderon, referring to Israeli Prime Minister Benjamin Netanyahu.

He has met with only a handful of families — days after President Biden and members of his administration first reached out to them — and has provided few assurances.

Kalderon, who also holds French citizenship, has met with French diplomats, including former prime minister Manuel Valls. But she is terrified that her own government, in preparing for a full-scale invasion of Gaza, may cast her children off as collateral damage.

“We are simple people; we are good citizens,” she said. “We gave whatever we could to our country. It’s the Israeli government that just forgot us.”