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So when she learned that the company intended to let her go, Ms. Paulin hired a lawyer.
In April 2009, Ms. Paulin was invited to meet with Claire Héry, Ikea's head of human resources for France. When she arrived at that meeting, she was surprised to find that the French unit's chief executive at the time, Mr. Baillot, was also present.
The two executives, Ms. Paulin said, accused her of fraudulently exaggerating her illness — although she said they offered no evidence to support their claims.
She said she left the encounter confused and distraught, feeling "robbed of my self and my reputation." A few days later, Ms. Paulin said, she attempted suicide.
Ikea, through its lawyer, Emmanuel Daoud, declined to comment on Ms. Paulin's account of the meeting.
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Ms. Héry, the human resources chief, was among the executives dismissed in 2012, although she is not a target of the court's investigation. Her lawyer, Olivier Baratelli, did not respond to emailed questions seeking comment.
Gérard Vergne, a lawyer for Mr. Baillot, declined to comment. Mr. Baillot left Ikea France in December 2009 for a job within the parent company's management team before being dismissed last year in the wake of the spying claims.
Even after the meeting, Ms. Paulin pressed her case, and in 2010 a judge ruled that her firing was "devoid of real and serious justification."
She did not seek reinstatement, but was awarded nearly €60,000 in compensation. Still, she said, the reason her bosses had leveled their accusations at her remained a mystery.
The matter might have ended there, were it not for a cache of company emails that were leaked to the French news media in early 2012.
The emails, now part of the court record, seemed to indicate extensive personal surveillance by Ikea in France dating back as far back as 2002.
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The trove of messages, many apparently written by Jean-François Paris, the French unit's head of risk management, exposed details of Ikea's investigations of Ms. Paulin and dozens of others. Mr. Paris was dismissed after the company's internal review and is named in the judge's investigation.
Mr. Paris has acknowledged his role to French investigators, said his lawyer, Étienne Bataille. But Mr. Paris insists that his activities were approved by top managers of Ikea France — and that on several occasions they were conducted at management's direction. "There is no question it was a widespread practice," Mr. Bataille said of the spying.
One of the emails from Mr. Paris, dated Dec. 11, 2008, was addressed to a private detective, Jean-Pierre Fourès. He was asked to confirm whether Ms. Paulin had traveled to Morocco over the preceding several months and if she owned property there.
Mr. Fourès's reply confirmed both to be true and included a startling attachment: scanned images from Ms. Paulin's passport, showing her Moroccan entry and exit stamps. To obtain those, the court documents show, Mr. Fourès had arranged for someone posing as an employee of Royal Air Maroc to persuade Ms. Paulin to fax copies of her passport in order to claim a free ticket offer.
Didier Leroux, a lawyer for Mr. Fourès, did not respond to requests for comment.
Under the subject line "dirty scam," Mr. Paris described Ms. Paulin as "a person who has been on medical leave for several months" and provided the dates, "obtained through outside sources," of her easyJet flights. He also asserted that Ms. Paulin had made the trips without informing her Social Security office.
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Citing Ms. Paulin's stature as a senior manager, Mr. Paris wrote, "We cannot tolerate this situation." Subsequent messages to the detective also disclosed details of Ms. Paulin's personal bank account.
"Until I saw those emails, I had not understood the depths of their suspicion, the paranoia," Ms. Paulin said. "They really believed I was playacting."
In transcripts of police interviews, Mr. Paris and his colleagues in the risk management department acknowledged receiving frequent requests from Ikea store managers across France for criminal background checks, driving records and vehicle registrations — though only a fraction of those inquiries uncovered a notable offense. Usually the requests were limited to one or two people after a theft or a complaint of harassment among employees.
But sometimes lists containing dozens of names of employees or job applicants were submitted for vetting, and then forwarded to one of a handful of trusted private investigators for processing.
The company has publicly expressed regret that certain managers took actions that were "contrary to our values and ethics standards" and says it has included respect of individual privacy in a new code of conduct.
Beyond that, however, Ikea has remained largely silent. "No one has ever called or come personally to apologize for what was done to me," Ms. Paulin said. "That's the gesture I would have expected — not some big investigation. But I've never gotten that."