It was a chilly January evening, and Khadija Abd and her family had just finished supper at their farm when the two men with guns burst into the room.

One wore civilian clothes, the other an army uniform. They said they were from the Iraqi army’s 20th Division, which controls the northern Iraqi town of Badoush. In fact, they were Islamic State group militants who had come down from the surrounding mountains into Badoush with one thing on their mind: Revenge.

Around 13 more gunmen were waiting outside. The fighters pulled Khadija’s husband and his two brothers into the yard and shot them dead, leaving them in a pool of blood _ punishment for providing information to the Iraqi military.

In this April 2, 2019 photo, an Iraqi army 20th division soldier uses his AK-47 riffle to knock on a door during a nighttime raid near Badoush, Iraq. (AP Photo/Felipe Dana)

“How can we live after this?” Khadija said. The three brothers were the providers for the entire family. “They left their children, their livestock, their wives, and their elderly father who doesn’t know what to do now.”

A year and a half after the Islamic State group was declared defeated in Iraq, the militants still evoke fear in the lands of their former so-called caliphate across northern Iraq. The fighters, hiding in caves and mountains, emerge at night to carry out kidnappings, killings and roadside ambushes, aimed at intimidating locals, silencing informants and restoring the extortion rackets that financed IS’s rise to power six years ago.

It is part of a hidden but relentless fight between the group’s remnants waging an insurgency and security forces trying to stamp them out, relying on intelligence operations, raids and searches for sleeper cells among the population.

The militants’ ranks number between 5,000 and 7,000 fighters around Iraq, according to one Iraqi intelligence official.

"Although the territory once held by the so-called caliphate is fully liberated, Daesh fighters still exhibit their intention to exert influence and stage a comeback," said Maj. Gen. Chad Franks, deputy commander-operations and intelligence for the U.S.-led coalition, using the Arabic acronym for the group.

“How can we live after this?”

— Khadija Abd

In towns around the north, Iraqi soldiers knock on doors in the middle of the night, looking for suspects, based on intelligence tips or suspicious movements. They search houses and pull people away for questioning.

Anyone is seen as a potential IS collaborator or sympathizer. In February, Human Rights Watch accused authorities of torturing suspects to extract confessions of belonging to IS, an accusation the Interior Ministry has denied. Detainees are pushed by the thousands into what critics call sham trials, with swift verdicts _ almost always guilty _ based on almost no evidence beyond confessions or unaccountable informants’ testimony. The legacy of guilt weighs heavily especially on women and children, who face crushing discrimination because of male relatives seen as supporting IS.

In this April 5, 2019 photo, a woman holds her daughter as she answer questions by Iraqi army 20th division soldiers during a raid in Badoush, Iraq. (AP Photo/Felipe Dana)

AP journalists embedded with a battalion of the 20th Division last month and witnessed several of its raids at Badoush.

Badoush, on the Tigris River just outside the city of Mosul, is a key battleground because it was once one of the most diehard IS strongholds.

In the summer of 2014, it was a launching pad for the militants’ blitz that overran Mosul and much of northern Iraq. IS built a strong financial base by extorting money from the owners of Badoush’s many industrial facilities. Security officials estimate two-thirds of its population _ which numbered around 25,000 before the war _ were at one point members or supporters of the group.

In this April 2, 2019 photo, an Iraqi army 20th division soldier asks for documents at a checkpoint near Badoush, Iraq. (AP Photo/Felipe Dana)

Now the population is divided. Residents who suffered at the hands of IS or lost loved ones to the group are suspicious of neighbors they believe still support the militants. Within families, some members belonged to the group and others opposed it.

The Badoush area alone has seen 20 IS attacks, from bombings to targeted killings, since it was retaken from the militants in March 2017, according to the Kurdish Security Council. The militants brag about the attacks in videos that show fighters storming houses and killing purported “apostates” and spies.

“The operations that we do now rely on intelligence by following up the families of Daesh,” said Maj. Khalid Abdullah Baidar al-Jabouri, commander of a battalion in the 20th Division, speaking at his base just outside Badoush.

Distrust runs deep among the residents.

In one raid witnessed by the AP, troops banged on the door of a man who had returned to Badoush a day earlier. He had fled town just before the IS takeover in the summer of 2014 and stayed in the Kurdish town of Sulaimaniyah throughout their rule. But his father and one of his brothers remained and joined IS.

In this April 5, 2019 photo, an Iraqi army 20th division soldier searches a house during a raid in Badoush, Iraq.(AP Photo/Felipe Dana)

When the man returned, a local sheikh immediately notified the military. In the raid, the soldiers searched the house and checked his phone records for any suspicious calls abroad.

They asked him about his father and brother. “I swear, they destroyed my life,” the man said. When asked about IS, he insisted, “I never came face to face with them.”

The soldiers took him away for questioning, as his three little sisters shook and cried with fear. He was later released.

“The operations that we do now rely on intelligence by following up the families of Daesh.”

— Major Khalid Abdullah Baidar al-Jabouri

On another occasion, an informant told the army he had spotted explosives-laden suicide belts in the mountains while out picnicking and looking for truffles. Presumably, they had been dropped off there for attackers to retrieve and use. Wearing a balaclava to keep his identity secret, he led the army to the spot, where they found the belts and detonated them remotely.

“People in the town are very cooperative,” says Mohammed Fawzi, an intelligence officer. “But don’t forget that in one house one person was with Daesh and another member was killed by them. It’s very complicated.”

Among the most chilling IS attacks was the Jan. 3 killing of the three Abd brothers, carried out with brutal precision.

The strangers claiming to be soldiers who entered the Abd’s house said they just wanted to ask a few questions and that it wouldn’t take long.

Khadija Abd was immediately suspicious. Her husband, Inad Hussein Abd and two of his brothers, Abdulmuhsin and Mohammed, were informants for the Iraqi military and knew the 20th Division’s soldiers personally. So why didn’t they recognize these men?

After searching the house, the intruders turned aggressive. They dragged the three brothers outside and beat them. When Khadija tried to stop them, she was beaten too. The fighters put her, the other wives on the farm and their children in a room and told them, “If anyone comes out, we shoot you in the forehead.”

Khadija could hear the men murmuring outside until 10 p.m. in a dialect of Arabic she couldn’t understand. Then it was silent. All they heard was the barking of dogs. Khadija thought the men had taken the three brothers away.

At dawn, she went to get water from the well. She spotted her husband’s yellow sleeve in the grass. All three brothers lay on the blood-soaked ground. The militants had used silencers, so the family never heard the gunshots.

Instinctively, she looked for a mobile to call for help. “Honestly, I couldn’t even cry. I didn’t cry or scream,” she said.

Memories of the attack return to Khadija in her dreams _ how her daughters screamed “Dad! Dad!” when they saw his body, how one tried to pull out a bullet out of her dead father’s cheek. “Mom, it won’t come out,” she told Khadija. Her son is now too afraid to leave his room.

To the children, it’s the army that killed their father, she said. “They don’t understand anything that’s going on.”