Abu Salim was Tripoli's most notorious prison, home to political detainees, accused Islamists, and ordinary criminals alike. On June 28, 1996, several inmates escaped, and as punishment, the administration slashed food rations for the entire population. Prisoners revolted, seizing two guards during a food distribution. One guard was killed. Security forces opened fire, killing six prisoners and wounding about twenty. Government negotiators arrived, among them Abdullah Senussi, Gaddafi's intelligence chief. The prisoners' representatives made straightforward demands: improved conditions, medical care for the sick, and trials for those held without charge. Senussi refused the request for trials but agreed to the remaining conditions once the surviving guard was released. The prisoners accepted the terms.

What happened next betrayed every promise made. One hundred and twenty injured and sick prisoners were loaded onto buses with assurances they would receive medical care. They were never seen again. The following morning, June 29, guards herded prisoners from their cells into the central courtyards. From the rooftops above, gunmen opened fire. The killing continued through that day and into the next. More than 1,200 people died. About 270 inmates from Blocks 1 and 2 were spared -- apparently because the keys seized from the guards during the revolt did not fit their cell locks, and the prison commander assumed they had not participated in the uprising. According to writer Hisham Matar, whose father was among the disappeared, the dead were initially buried in shallow graves in the six courtyards where they had been executed. Months later, the bodies were exhumed, the bones ground up, and the remains dumped into the sea.

The Libyan government rejected all allegations of a massacre for eight years. It was not until April 18, 2004, that Gaddafi publicly acknowledged the killings had occurred. Even then, the regime's account was misleading: officials claimed the violence arose from confrontation with rebels of the Libyan Islamic Fighting Group, and asserted -- without evidence -- that some two hundred guards had also been killed. Gaddafi eventually agreed to pay compensation to victims' families, but the process was slow, opaque, and widely seen as an attempt to buy silence rather than deliver justice. The captured Mansour Dhao, a senior Gaddafi regime figure, later confirmed the massacre in a BBC interview, lending additional weight to the accounts that survivors and human rights organizations had assembled.

In 2007, ninety-four families of the dead and disappeared filed a lawsuit at the Benghazi North District Court, seeking simply to learn the fate of their relatives. The court rejected the case, but the Benghazi Appeals Court ruled in June 2008 that the state must reveal what happened to the missing detainees. Eighty more families joined the suit. Their lawyer, Fathi Terbil, was arrested multiple times. In January 2010, the regime blocked YouTube after videos surfaced showing Benghazi demonstrations by Abu Salim families. When the Arab Spring swept through Tunisia and Egypt in early 2011, Terbil was among the first arrested, on February 15, in a preemptive attempt to prevent unrest. It had the opposite effect. The Abu Salim families gathered to demand his release. Their protest swelled into the mass demonstrations of February 17 that ignited the Libyan revolution. Senussi himself reportedly asked Terbil to call off the protests. The families refused to stop.

After Gaddafi's overthrow, the National Transitional Council announced in September 2011 that a mass grave had been located outside Abu Salim prison, identified through information from captured former regime officials. Investigators believed 1,270 people were buried there, but when CNN and other media visited the site, they found only what appeared to be animal bones. The NTC acknowledged it needed international assistance for proper forensic analysis and DNA identification. The search for the dead of Abu Salim -- many of them young men whose families waited decades without answers -- remains unfinished. A memorial monument was later erected at the site. For Hisham Matar, who chronicled his father's disappearance in the memoir "The Return," Abu Salim represents not just a place of death but a wound in Libyan society that has never properly healed.