After a video surfaced showing Syrian rebels executing four pro-government militiamen in Aleppo, more than two dozen rebel leaders—at the urging of human-rights groups—signed a pledge on August 8 to stop executing and torturing captives in their battle to overthrow Syrian President Bashar al-Assad.

Yet as The Daily Beast discovered during a disturbing and at times surreal visit to a detention center in Al Bab in northeastern Syria on August 10, members of the Free Syrian Army (FSA), the main rebel-fighter force, still appeared to be involved in torture and abuse.

Their instruments of pain were on clear display: in the small dusty yard in front of the facility, not far from where guards lounged and smoked cigarettes, wooden sticks and iron bars were scattered in the shade, still coated with blood.

Downstairs in the basement, where eight prisoners were being held in a large room, there was a bed frame in a corridor with ties still attached presumably used to pin the arms and legs of captives. There was a large water vat and plastic pipes by the bed frame, which appeared to be used for some sort of water torture.

As he ordered the guards to unlock the door leading to the prisoners, the detention center’s warden, a short but powerfully built native of the city of Homs in west Syria, Yousef al-Shawash, insisted at first that the captives were in excellent physical condition and enjoying the comforts of home. “They eat the same as us. We look after them very well,” said al-Shawash, who lost family members in Homs earlier this year. “We never beat them. Ask them who fetches them food and gets medicine for them and gets anything they want? They will all tell you how much I do for them,” he barked as he faced his charges.

The sorry appearance of the eight captives belied the warden’s words. All were sitting barefoot on mattresses around the walls of their fetid, dimly lit room. They appeared terrified of the guards, flinching when they approached. All eight sported clear signs of bruising and some clearly had sustained serious injuries.

Four were suspected al-Assad supporters, two were Syrian army soldiers and another two were members of the Shabiha, a widely-feared government militia. Five of the captives shook their heads despondently when asked if they wanted to be interviewed by a foreign journalist.

The pledge signed by the rebel army last week states that prisoners’ rights will be preserved and that "any form of torture, rape, mutilation, or degradation” will be shunned.

The FSA also emphasized their commitment to “human rights, for which we struggle today and which we intend to implement in the future Syria.” That is the moral foundation of their struggle against al-Assad, they say.

That commitment was not on display in the facility in Al Bab, a town where this week, grisly video footage posted on YouTube showed rebels hurling bodies off the rooftops of the main post office. Al Bab rebels insist the footage is from a month ago, and that the bodies are of government snipers who were killed in the heat of battle.

The Al Bab detention center was far from the heat of battle and the extent of the injuries inflicted on three of the prisoners became more evident during brief, supervised interview sessions in a well-lit room.

One soldier, a 19-year-old who had been arrested a month earlier in Jarabulus, a town in northeast Syria, was in the best condition of the three, but had serious bruising and was highly anxious. He had originally claimed to be a deserter, but was nabbed by the FSA after being spotted talking with military intelligence. He declined to give his name and insisted his jailer was treating him like his mother would.

The Shabiha militiamen were in a much sorrier state. One 30-year-old Shabiha member from Aleppo, who declined to give his name, said he’d also been captured in Jarabulus. He took up with the militia just two months ago and was caught ferrying ammunition to snipers, he said. He refused to answer what else he had done with the militia. He had great difficulty walking; his feet were badly swollen and he had black eyes. Struggling to sit up, his breathing was heavily labored and each inhalation caused him obvious pain. He complained of broken ribs but said no doctor had visited the detention center.

When asked if his injuries had been caused in battle, he looked at al-Shawash apprehensively trying to gauge how he should answer, eventually responding meekly: “He beat me.” The stocky jailer intervened, agreeing: “We hit him a bit during interrogations. But we get him medicines.”

The second Shabiha militiaman, 28-year-old named Ahmed al-Daran, was in equally bad shape. Hardly able to hobble into the room on his bruised and engorged feet, he sported black eyes. He was covered with deep bruises and his hands were grotesquely swollen. A diminutive but tough man—his arms were covered in tattoos—he shook his head and laughed quietly when asked how he’d sustained his injuries.

It wasn’t difficult to tell: in the background during the interview a chorus of screams and groans erupted from an adjacent room accompanied by a cacophony of whacks and thuds. The jailer and guards remained unperturbed, although the beatings next door ceased when an opposition activist arrived and signaled for the guards to stop.

A Sunni Muslim—most Shabiha tend to be drawn from President al-Assad’s Alawite minority—Ahmed said had was a smuggler from Aleppo and had joined the militia when offered money to bust-up anti-al-Assad demonstrations and to beat up opposition activists. He was paid $15 for each demonstration he helped disrupt.

Ahmed’s jailer at first said he and his fellow guards never hit any of the prisoners to get information or to extract a confession; he said the beatings only occurred after they confessed or when the rebels had clear evidence of guilt. Later he changed his story, arguing the only way to secure information was to beat them, concluding that when found guilty “they needed to be punished” anyway.

Human-rights groups have accused both al-Assad's forces and the rebels of committing violations including torture and killing of captives, although most say the violations are more extensive when it comes to the government side.

The footage that emerged showing rebels executing four suspected Shabiha militiamen in Aleppo in early August turned the spotlight on the conduct of the Free Syrian Army, whose commanders argue that only those who had been involved in the most egregious killings are executed while the others are held for later trial before newly formed religious courts headed by local mosque leaders in rebel-controlled towns.

“They argue they are abiding by Islamic law,” says Ole Solvang of Human Rights Watch. “On torture they are receptive and had promised to discontinue the practice. But there seems little will to stop it and on the executions they are even more difficult. They ask 'Why should they observe human-rights law when al-Assad doesn’t?'”