This is the room where my whole family was killed, says Safa Younes.

Bullet holes pepper the front door to the house in the Iraqi town of Haditha, where she grew up. Inside the back bedroom, a colorful bedspread covers the bed where her family was shot.

This is where she hid with her five siblings, mum, and aunt when US marines stormed into their home and opened fire, killing everyone apart from Safa, on 19 November 2005. Her dad was also shot dead when he opened the front door.

Now, 20 years on, a BBC Eye investigation has uncovered evidence that implicates two marines, who were never brought to trial, in the killing of Safa's family, according to a forensic expert.

The evidence - mainly statements and testimony given in the aftermath of the killings - raises doubts about the American investigation into what happened that day and poses significant questions over how US armed forces are held to account.

The killing of Safa's family was part of what became known as the Haditha massacre, when US marines killed 24 Iraqi civilians, including four women and six children. They entered three homes killing nearly everyone inside, as well as a driver and four students in a car, who were on their way to college.

The incident triggered the longest US war crimes investigation of the Iraq war, but no-one was convicted of the killings.

The marines said they were responding to gunfire after a roadside bomb went off, killing one of their squad members and injuring two others.

However, Safa, who was 13 at the time, recalls: We hadn't been accused of anything. We didn't even have any weapons in the house.

She survived by pretending to be dead among the small bodies of her sisters and brother - the youngest was three years old. I was the only survivor out of my entire family, she claims.

Four marines were initially charged with murder, but they gave conflicting accounts of the events, and over time US military prosecutors dropped charges against three of them, granting them immunity from further legal action.

That left squad leader Staff Sergeant Frank Wuterich as the only one to face trial in 2012.

In a newly discovered audio recording from Wuterich's trial, the most junior member of the squad, Lance Corporal Humberto Mendoza, was questioned and re-enacted events at Safa's house. He admits to killing Safa's father when he opened the front door, but claimed he was following orders.

Forensics expert Michael Maloney, who investigated the killings, pointed to discrepancies in the testimonies that suggest the involvement of Mendoza and another marine, Lance Corporal Stephen Tatum, during the shooting of Safa's family.

Despite the evidence and witness testimonies, concerns remain over the military's commitment to accountability, as no one has been held criminally responsible for the deaths that day.

Now 33, Safa still lives in Haditha and has three children. She expresses disbelief that no marine has been punished for her family's deaths, underscoring the ongoing trauma and quest for justice.