BAGHOUZ, Syria - A hesitation on a simple question or a callus on a trigger finger -- it doesn't always take much for US-backed forces to spot potential jihadists hiding among fleeing civilians.
At a desert outpost held by the Syrian Democratic Forces near the Iraqi border, trucks stream in carrying men, women and children from he ever-shrinking last bastion of the Islamic State group.
"Men over here, women on the other side," one SDF member calls out, ushering those who have fled into orderly lines near the frontline village of Baghouz.
Men queue up in front of an SDF official, who registers each new arrival.
He records each man's fingerprints with a small digital reader, takes their photo, and jots down their name and nationality.
Opposite him, a man with a thick beard stutters when he is asked his country of origin. He fumbles for words, then answers: "Iraq."
He is passed on to a colleague from the SDF special forces, who then ferries him on to a third investigator for even more questions.
After they are interrogated, the men are then led to the side, where they sit on the ground in crowded, neat lines, an identical distance between them.
"Sometimes you feel you have an ISIS fighter in front of you from the way he speaks or when he hesitates to reply," an interrogator tells AFP.
"Or if you find traces on his hands that show extensive use of a trigger, or on his shoulders from carrying a cartridge pouch," he says, asking to remain anonymous for his security.
- 'Scared' -
Members of the US-led international coalition backing the SDF stroll around the area, but it is not immediately clear what their role is in the screening process.
Backed by coalition air strikes, the SDF have since September pressed a battle to expel IS from the last shred of the "caliphate" they proclaimed in 2014.
The Kurdish-led alliance has whittled down that pocket to just a few hamlets in the eastern province of Deir ez-Zor, sending thousands of people fleeing.
Some 32,000 people have escaped into SDF-held territory since early December, according to the Syrian Observatory for Human Rights.
They included more than 2,700 ISIS jihadists, the Britain-based war monitor says.
Among the new arrivals in the desert, another bearded man stands in line waiting to be assessed.
He says he stayed behind when his family fled a week earlier: "I was scared I'd be detained."
But his family encouraged him to leave after they reached a Kurdish-held camp for ISIS relatives in Syria's northeast.
"They told me, 'Come. Nothing will happen to you,'" he says.
In their own section, women too are searched and screened.
Female SDF fighters lift up the black face veil of each new arrival to see their face and inspect their scant belongings.
When they encounter a woman who is neither Syrian nor Iraqi -- an "immigrant", they say -- they also record her fingerprints and take her photo.
- 'Slaughter you' -
After being vetted, women, children, and men not suspected of belonging to the extremist group are transported north to the Kurdish-run camp of Al-Hol.
"The aim of this security operation is to know who the displaced are," says Mohammed Suleiman Othman, an official in charge of their transfer.
"Are they civilians, or fighters hiding" among them?
Among the women waiting, several said a baby died during the night from the cold and had to be buried. Two women, they say, gave birth in the open.
A truck draws up and they all rush towards it. SDF fighters have arrived to distribute bread.
Sitting on the ground, Amina Hajj Hassan, 28, says she fled Baghouz with her five-year-old-son after most of the village came under SDF control.
Her husband -- a "modest employee" of the jihadist group -- fled five months ago, says the young Syrian woman from the northern province of Aleppo.
He made it to Turkey where he now works, she says.
"I wanted to leave when the bombardment... started months ago, but they told us: 'The Kurds will slaughter you'."
Next to her, Noura al-Ali says she is wracked with worry after her husband was detained, though "not one day" did he join ISIS.
"He worked at a restaurant," says the 18-year-old, also from Aleppo province.
"I used to listen to music in secret," she adds, whereas ISIS forbade it.
Her only wish is "to go with my husband to join our family in Turkey".
