French in fear as new killer on a motorcycle stalks Paris suburbs

Four people are shot dead with the same weapon, but detectives think two gunmen may be involved

Forensic detectives look for clues at the flats in Grigny where a woman aged 47 was shot on Thursday (Getty Images)

Two weeks after the "scooter assassin" Mohamed Merah died in shootout with police in Toulouse, another serial killer who rides a motorcycle may be at large in the Paris suburbs.

A 47-year-old woman was shot in the head on Thursday, bringing to four the number of people killed with the same revolver within a six-mile area since November. In all the cases, the gunman was seen escaping on a motorbike.

Investigators are, however, wrestling with a mystery. They believe the first murder was committed by a different person, using the same gun. Only the second, third and fourth killings – in which random victims were shot in the head at close range – appear to have been carried out by the same man.

The later series of three murders began in February before Merah, a 23-year-old al-Qa'ida fanatic, launched his shooting spree in south-west France, killing seven people in Montauban and Toulouse before he was shot himself by marksmen. The possibility of a copycat has, therefore, been excluded.

For the time being, authorities have also ruled out theories that a second radical Islamist or other terrorist may be responsible. But they fear the killings, following Merah's seven murders in eight days, could cause a new wave of panic.

More than 100 detectives have been assigned to the case. Every motorbike in the southern suburbs of the capital is being checked. A local state prosecutor, Marie-Suzanne Le Quéau, said yesterday that the methods used in the killings were "not identical".

"In the first incident, the victim [a woman of 37] received multiple shots to her body. In the other three, death was due to shots in the head," she said.

In December, a 46-year-old minor criminal confessed to the first of the murders. He said he shot the victim, named as Nathalie D, in the stairwell of her apartment block at Juvisy-sur-Orge in the Essonne area after she broke off their relationship. He later retracted his confession but remained in custody while investigations continued.

On 22 February, a man aged 51 was shot in the underground car park of the same building with the same gun. At first police believed the killing might have been carried out by a friend or accomplice to eliminate a witness to the first murder. This theory fell apart when the same gun was used again on 17 March to shoot an 81-year-old man in the hallway of his apartment block in Ris-Orangis, a few kilometres away. He had no links with the other victims.

The fourth killing, in Grigny on Thursday, of a 47-year-old woman of Arab origin has left investigators even more baffled. The victim, a widow with a son aged 18, was shot three times in the hallway of her apartment block. She had no connections with the three other victims.

Police sources told Le Monde newspaper yesterday that it was possible the later killings were random acts by an accomplice to distract suspicion from the ex-boyfriend who remains in prison. Alternatively, the sources said, the gun used in the first crime might have been "hired out" to another killer. In all cases the killer was seen escaping on a high-powered motorcycle.