Hezbollah security official Mohammed Ali Younes was found killed on Saturday near the southern Lebanese town of Zawtar El Gharbiyeh.
He and his companion were victims of an ambush shortly after coronavirus-related curfew was imposed on Saturday evening.
The companion survived and was being treated in hospital, said Hezbollah.
Informed sources told Asharq Al-Awsat that Younes acted as a security official in the area and was tasked with anti-espionage missions against Israeli agents and Mossad spies.
His corpse was discovered in a remote area between the towns of Qaaqaaiyet El Jisr and Zawtar El Gharbiyeh. A Lebanese security official told the Associated Press that Younes was shot with four bullets in the chest and had at least two stab wounds.
The motive behind the killing was no immediately clear, Lebanese security officials said. They spoke on condition of anonymity because they were not authorized to talk to the media.
Three vehicles, including an SUV, were involved in ambushing Younes, who was reportedly working on an important case before his killing.
Hezbollah confirmed that a suspect has been arrested.