The victim's been identified as Mansour Saad Awad, who worked on a poultry farm near the area of Mechili, which is in the province of Cyreneica on the coast of eastern Libya.
No one has come forward to claim responsibility for the murder, but the manner of it implies Islamic State was behind it.
The Catholic news agency Fides reported the murder on the same day the head of the Coptic Orthodox Church, Patriarch Tawadros II, met personally with the families of the 21 copts who were killed by Islamic State last month.
In the meeting, Patriarch Tawadros II gave the familiies certificates of their death which offically made them martyrs. He also said the 21 copts "have enriched the Church with their blood".
The current Libyan government has requested the United Nation's permission to import significant amounts of tanks, war aircraft, weaponry and ammunition to deal with internal conflicts between different political and religious factions such as Islamic State.
The UN imposed an arms embargo on Libya in 2011, after the Western-supported ousting of Colonel Muammar Gaddafi.
Proponents say he was an undemocratic dictator who abused human rights and achieved power in a coup d'etat, however critics say Gaddafi defended Libyan and African interests, the West had no right to depose him, and doing so has given extremists like Islamic State a chance to seize power.