He believes they are issued with fake Somali fishing licences by powerful local backers who also provide them with gunmen for protection.

Eight days before his death, he published a column in which he described López Serrano as spoiled, "good for chatting but not business" and a "weekend gunman with a prop pistol".

The gunman is alleged to have also confessed to an earlier shooting in the nearby town of Wormhout, according to AFP news agency.

The attacks were reported by multiple sources, including security blogs, which said the gunmen, believed to be allied to the Islamic State group, launched two simultaneous attacks in Chatoumane village.

The gunman — who was also killed — was a former student of Giovanni’s, and she had alerted school authorities previously about his troubling behavior in her class.