Mystery sniper is killing off ISIL's high command in Libya
As befits all the best practitioners of his shadowy trade, no-one is quite sure whether he is one man or many, or even simply an urban legend.
But after a string of assassinations of its local henchmen, the Islamic State's new "Caliphate" in the Libyan city of Sirte is abuzz with talk that an anti-Isil sniper is at work.
In recent weeks, no fewer than three Isil commanders in Sirte have been shot dead from long range, according to local media.
The killings - reported to be the work of a sniper who honed his skills in Libya’s uprising against Colonel Gaddafi - are said to have sowed panic among Isil's forces in the city, who have carried a string of arrests and executions in a bid to track down the culprit.
The Sirte assassin's most recent casualty, according to social media reports from Sirte, was Abdullah Hamad Al-Ansari, an Isil commander from southern Libyan city of Obari, who was shot dead on January 23 as he left a city centre mosque.
The birthplace of Libya's late Colonel Gaddafi, Sirte has been under Islamic State control since last summer, Libyan intelligence officials estimating that there may now be up to 2,000 jihadist fighters now based there.
The port city’s new masters have made brutal examples of opponents, via a regime of floggings and beheadings enforced by black-masked religious police.
But while the group's leaders now enjoy unchallenged rule on the streets, that does not appear to have left them immune to long-range attack from Sirte's many battle-scarred buildings.
Tales of the mystery marksman are believed to have found a ready audience among the city's population, few of whom actively support the city's new hardline rulers.