A US jury on Tuesday awarded 42 million dollars (£33 million) to three former detainees of Iraq’s notorious Abu Ghraib prison, holding a military contractor responsible for contributing to their torture and mistreatment two decades ago.

The decision of the eight-person jury came after a different jury earlier this year could not agree on whether Virginia-based CACI should be held liable for the work of its civilian interrogators, who worked alongside the US army at Abu Ghraib in 2003 and 2004.

The jury awarded plaintiffs Suhail Al Shimari, Salah Al-Ejaili and Asa’ad Al-Zubae three million dollars (£2.34 million) each in compensatory damages and 11 million dollars (£8.6 million) each in punitive damages.

The three gave evidence that they were subjected to beatings, sexual abuse, forced nudity and other cruel treatment at the prison.

They did not allege that CACI’s interrogators explicitly inflicted the abuse themselves, but that CACI was complicit because its interrogators conspired with military police to “soften up” detainees for questioning with harsh treatment.

CACI said: “For nearly two decades, CACI has been wrongly subjected to long-term, negative affiliation with the unfortunate and reckless actions of a group of military police at Abu Ghraib prison from 2003 through 2004.

“To be clear, no CACI employee has ever been charged, criminally, civilly, or administratively in this matter. CACI employees did not take part in nor were any of our employees responsible for these disturbing events.”

Baher Azmy, a lawyer for the Centre for Constitutional Rights, which filed the claim on the plaintiffs’ behalf, called the verdict “an important measure of justice and accountability” and praised the three plaintiffs for their resilience, “especially in the face of all the obstacles CACI threw their way”.

The trial and subsequent retrial was the first time a US jury heard claims brought by Abu Ghraib survivors in the 20 years since photos of detainee mistreatment, accompanied by smiling US soldiers inflicting the abuse, shocked the world during the US occupation of Iraq.

CACI had argued it was not complicit in the detainees’ abuse. It said its employees had minimal interaction with the three plaintiffs in the case and any liability for their mistreatment belonged to the government.

As in the first trial, the jury struggled to decide whether CACI or the army should be held responsible for any misconduct by CACI interrogators.

The jury asked questions in its deliberations about whether the contractor or the army bore liability.

CACI, as one of its defences, said it should not be liable for any misdeeds by its employees if they were under the control and direction of the army, under a legal principle known as the “borrowed servants” doctrine.

Lawyers for the plaintiffs argued that CACI was responsible for its own employees’ misdeeds.

The lawsuit was first filed in 2008 but was delayed by 15 years of legal wrangling and multiple attempts by CACI to have the case dismissed.

Lawyers for the three plaintiffs argued that CACI was liable for their mistreatment even if they could not prove that CACI’s interrogators were the ones who directly inflicted the abuse.

The evidence included reports from two retired army generals, who documented the abuse and concluded that multiple CACI interrogators were complicit in the abuse.

Those reports concluded that one of the interrogators, Steven Stefanowicz, lied to investigators about his conduct and that he likely instructed soldiers to mistreat detainees and used dogs to intimidate detainees during interrogations.

Stefanowicz testified for CACI at trial through a recorded video deposition and denied mistreating detainees.