Guidici had frequently covered separatist movements on the French island of Corsica as a reporter for the regional newspaper Nice-Matin. He was also the author of Crepuscule des Corses ("Twilight of the Corsicans"), a critical assessment of Corsican society that was published in 1997.
In an interview granted to the Madrid daily El Pais last year, Guidici said "a part of Corsica's political class has aligned itself with a hard-line segment of the nationalist movement that never unequivocally condemned violence."
Local police have launched an investigation into Giudici's murder, according to The Associated Press.
For over two decades, Corsican separatist groups have been pursuing a sometimes-violent campaign against the French government. Corsican demands range from greater autonomy to full independence.