PARIS, May 25 (AFP) - French police Tuesday issued an all-points alert for a shepherd suspected of firing the bullets in the 1998 hit-squad killing of France's top official on the troubled Mediterranean island of Corsica. Only a day after police said radical Corsican nationalists had confessed to taking part in the assassination, a photo of Yvan Colonna, son of a former Socialist parliamentarian, was distributed to police stations nationwide along with a warrant for his arrest. Colonna is believed to have fired the three bullets to the back of the head that killed Claude Erignac, then acting prefect of Corsica, on February 6 last year, sending shockwaves across France. Corsica has been the scene of dozens of killings and some 10,000 terrorist attacks in 25 years of separatist violence, but Erignac was the seniormost official in memory to be gunned down. Five other radical Corsican nationalists were being questioned by police, four of whom are said to have confessed Monday to being part of the squad who killed Erignac in a bid to inflame tension and win supporters to their separatist cause. The warrant described Colonna, aged 39, as "armed and dangerous." Police traced Erignac's alleged killers after a minute inquiry into calls made by mobile telephones in the heart of downtown Ajaccio, the island's capital, during the 80 minutes before and after his 9:00 p.m. murder there. Colonna's father Jean-Hugues, a 65-year-old former Socialist deputy, issued a public plea to his son to turn himself in. "Yvan, I want to say again that I love you, and that is why, and for the sake of your son, for yourself, for your defence, you must contact the police." The sudden arrest of Erignac's suspected killers 15 months after the event was announced on the eve of a censure vote over Corsica policy in the National Assembly, or lower house. With a healthy majority in parliament, the government of Socialist Prime Minister Lionel Jospin was not expected to be at risk when the motion called by the rightwing opposition was debated later Tuesday. But it is only the second censure vote faced in almost two years of office by Jospin and follows an embarrassing scandal that erupted early this month on the allegedly illicit activities of Erignac's successor, Bernard Bonnet. Bonnet, ironically, who was dispatched to clean up the island's murky politics in the aftermath of Erignac's murder, was sacked and placed behind bars this month on suspicion of ordering special police to set fire to a beachside restaurant. The charges of arson against the prefect caused the worst scandal yet faced by Jospin, with the opposition demanding heads roll among the cabinet on the grounds that ministers were either involved in the arson or should accept responsibility for the prefect's misdemeanours. Bonnet has claimed he acted alone and has cleared the government of all knowledge of his scheme to burn down restaurants built illegally, and operating without a license. The sacked prefect is said to have grown discouraged by local resistance to his anti-corruption drive. The arrest of his predecessor's alleged killers is thus expected to help the government save face during Tuesday's parliamentary debate and enable it to argue that it is indeed working to restore law and order in Corsica, which has a history of clannish mafia-style corruption. -=-=- 