The 24-year-old banged on a guard station window, pleading for help, but no one came to his aid.
The correctional officers failed to intervene even when his attacker stopped to get a drink and catch his breath, before beginning to beat an unconscious Hanni who was convulsing in a pool of blood for a second time.
Two minutes after he atopped his brutal assault, the prison guards finally entered the cell with handcuffs, the video obtained by the Associated Press shows.
As a result of the attack, Hanni suffered bleeding inside his skull and spent three days in a coma.
According to family members, he has been left with a brain damage, and his life will never be normal again.
The footage, which was shot in January, has prompted an investigating by the Federal Bureau of Investigation (FBI) as to whether the guards violated the civil rights of inmates at the Idaho Correctional Center.
The Corrections Corporation of America (CCA), which runs the notorious Idaho prison — also known as Gladiator school — said it was co-operating with federal agents in the investigation.
The CCA, the largest private prison company in the United States, has however expressed its annoyance at the release of the footage, claiming that it “poses an unnecessary security risk to our staff, the inmates entrusted to our care and ultimately to the public.”
In April, Hanni filed a lawsuit against the company, asking for punitive damages and compensation in an amount to be proven in court.
During his time at the Idaho prison on a robbery conviction, Hanni, who is a Muslim of Palestinian decent, had repeatedly told his family that he was being harassed by inmates despite reporting their actions to prison guards.
In one such incident his cellmate had broken his jawbone.
The lawsuit echoes other complaints lodged against the CCA in which other inmates allege they were knowingly exposed to violence and then denied proper medical care in an effort to cover up the extent of their injuries.
The American Civil Liberties Union has meanwhile said that the video confirms recent claims that US prisons foster a “culture of rampant violence.”
Source: Press TV