Police scour Europe for man whose family were buried in the garden

(GETTY)

French police searching for a man whose wife and children were found buried in his garden have widened the manhunt across Europe.

Xavier Dupont de Ligonnès was last seen on 15 April, six days before the bodies of his wife, his four children and their dogs were discovered in the family garden in Nantes, in western France. Autopsies have revealed they were "methodically" shot dead with a rifle while they were asleep about nine days before Dupont de Ligonnès disappeared.

The French authorities issued an international search alert on Saturday, but no arrest warrant has been issued. A picture nonetheless emerged over the weekend of a man with a compelling case to answer, and a string of evidence that seems to incriminate him.

In February Dupont de Ligonnès announced that his father had died and left him a .22 rifle, the same type of weapon that was used in the quintuple murder. For the last few months, he had been taking his sons to a shooting club to practise with the rifle, which was equipped with a silencer.

The club's president, Alain Neutre, said that Dupont de Ligonnès went for practise himself four times in the week before the killings. And Benoit Hérault, a shooting coach, said that he had enquired about using a silencer, AFP reported.

On 1 April, he told the rifle club that his sons would be unable to attend the following week. Three days later, he informed the school attended by his two youngest children, aged 13 and 16, that they were ill. Dupont de Ligonnès settled the school fees a week later, saying the family was moving away because he had found a job in Australia. Several of his friends were told the family was moving to America under a witness protection scheme as part of a drugs case.

Police have traced purchases of quicklime, hessian sacks, heavy-duty cleaning products and a spade to Dupont de Ligonnès. When the bodies were found under the patio, they were in hessian sacks.

The case has yielded surprises further afield. A few hours after the bodies were discovered on Thursday, a woman went to the police near Paris claiming that Dupont de Ligonnès owed her ¤50,000. She also said she was his mistress and that she feared for her life. She showed police a letter and text messages she said were from Dupont de Ligonnès.

He declared an annual income of only ¤4,000, according to the Nantes prosecutor. With this he was apparently able to afford to keep a two-storey house in Nantes, pay school fees for two children, and support his two eldest children, aged 18 and 21, at university. The family also owned several cars, including one which was registered in his name, but which neighbours said they had never seen.

In another twist, the disappearance of another woman has been linked to the case. Colette Deromme was seen for the last time on 14 April. She lived in Lorgues, southern France, 500 metres from the district of the town where the Dupont de Ligonnès family lived between 1992 and 1994.

Dupont de Ligonnès was last seen on 15 April when he abandoned his car after staying at a hotel in Roquebrune-sur-Argens, an hour's drive south of Lorgues. He had spent the night of 12 April in a five-star hotel in Vaucluse, 200km north of Lorgues. Investigators have acknowledged the coincidence but have not proved a link between the two cases.

Police are following up witness accounts that Dupont de Ligonnès has been spotted near Nice accompanied by a blonde woman.