The International Criminal Court has issued an arrest warrant for a senior Libyan military commander allied with Khalifa Haftar who is suspected of involvement in the deaths of 33 people in the eastern city of Benghazi.
Haftar is the controversial chief of the self-styled Libyan National Army (LNA), which now controls key Libyan oil ports.
Libya descended into chaos following the 2011 civil war that toppled and killed longtime ruler Muammar Gaddafi, and the country is now split between rival governments and militias.
The ICC document, seen by Al Jazeera on Tuesday, says: "Mahmoud Mustafa Busayf Al-Werfalli [is] allegedly responsible for murder as a war crime in the context of the non-international armed conflict in Libya."
The murders were committed "in seven incidents, taking place from on or before 3 June 2016 until on or about 17 July 2017, in Benghazi or surrounding areas", the warrant says.
Werfalli allegedly personally shot or ordered the execution of people who were either civilians or injured fighters, according to the document.
"There is no information in the evidence to show that they have been afforded a trial by a legitimate court, whether military or otherwise, that would comport to any recognised standard of due process," the ICC's judges say.
The charges are backed up by recordings of witness interviews, video material and other evidence, the warrant said.
One video purportedly shows Werfalli shooting a hooded and unarmed person and afterwards telling the dead body: "You have been misled by he who did you harm. You have been misled by Satan."
In another incident, Werfalli is allegedly seen in video footage reading from a document before personally commanding a firing squad which then shoots 15 people wearing orange jumpsuits and black hoods, the ICC's judges said.
"After reading the document, Mr Al-Werfalli says ...'Ready! Aim! Fire!," the judges said, after which the executioners shoot the prisoners in three groups of five.
Al-Werfalli and two other men then allegedly personally execute three people, before he orders the execution of yet another two others.
"The video depicting the incident, involving a total 20 executed persons, was posted on social media on 23 July 2017," the judges said.
Fatou Bensouda, ICC's chief prosecutor, called on Libyan authorities to arrest and hand over Werfalli to ensure his surrender to the ICC "without delay".
"Such egregious crimes, including the cruel and dehumanising manner by which they were perpetrated against helpless victims, must be stopped," she said.
In a statement, Heba Morayef, director of Amnesty International's North Africa Research, said the ICC's decision was "a significant step towards ending the rampant impunity for war crimes in Libya".
"The Libyan authorities must urgently comply with this arrest warrant and hand [Werfalli] over to the ICC to face his accusers in a fair trial," she said.
"This warrant sends a clear message that those who commit or order horrendous crimes are not above the law and will not go unpunished."
Werfalli, born in 1978, is a senior commander in the Special Forces Brigade, or al-Saiqa, which defected from the Libyan military after the 2011 uprising against Gaddafi.
He joined al-Saiqa after Gaddafi's fall and has "played a commanding role since at least 2015", the ICC's judges said in the arrest warrant.
Since then, al-Saiqa has been battling alongside forces loyal to Haftar in Benghazi.
Haftar is a dominant figure for factions in eastern Libya that have rejected the UN-recognised Government of National Accord (GNA), contributing to its failure to expand its power in the capital, Tripoli, and beyond.
Libya's eastern-based parliament, the House of Representatives (HoR), is a rival of the GNA and allied with Haftar.