MOTHER-of-three Evelyn Lund, 53, who had moved to France with her second husband Robert to start a new life, went missing with her Toyota Landcruiser just after Christmas 1999.
She had spent an afternoon with English friends living nearby.
Police searched the couple's luxury converted barn home in La Vaute, near Montpellier, alerted Spanish police and circulated hundreds of posters with her details across France.
More than 120 police officers were involved in the investigation which included a search of the countryside around the couple's home and use of military satellites.
Divers were drafted in to search around 200 lakes.
A team of French officers also visited Lancashire police to gather information on her disappearance.
Animal lover Mrs Lund left her farm and stables in Winter Hill, Darwen after she met and married Robert in 1994.
Her first husband and father of her children, Arthur Taylor, who worked for a large insurance firm, died of cancer in the early 1990s.
Mr Lund, who had been a tree protection officer with Blackburn with Darwen Council, was quizzed by police at the start of the investigation.
Last year French police scaled down the operation from a 10-men team to six.
Mr Lund was held by police for questioning for almost 24 hours and again for 12 hours during the investigation and items including his computer were confiscated by police.
The couple's remote home has been thoroughly searched and French police travelled to Lancashire during the investigation to speak to friends and family.
Five months after her disappearance, French police said they were treating the case as a murder inquiry.
Her daughters said at the time they had been convinced their mother had been murdered.
One of her daughters, Patricia Taylor, of Witton, told the Lancashire Evening Telegraph last year: "The whole family is convinced she has been murdered.
"All we can do now is wait for the French police to prove it."
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article