The body of a French teenager who went missing 13 months ago has been found after a long police search halfway across the country from where she was last seen, authorities have announced.

Police had been searching for the 15-year-old — referred to only as “Lina” in French media — since her mysterious disappearance on September 23 last year.

They had amassed thousands of reports, conducted hundreds of interviews and analyzed hundreds of vehicles.

But it was GPS data extracted from the presumed killer’s car that led to her discovery on Wednesday, in a wooded area in the central French Nievre region, some 310 miles from where she went missing in Alsace in the country’s east.

DNA testing enabled the body to be identified, said Alexandre Chevrier, Strasbourg’s acting chief prosecutor.

The teenager’s smartphone tracking signal was lost at 11:22 am on September 23, last year, as she was walking on a small road towards the station of Saint-Blaise-La-Roche, a hamlet of barely 250 inhabitants, to catch a train to Strasbourg where she was to meet up with her boyfriend.

A week later, police opened a probe into suspected kidnapping.

After months of fruitless investigation, police identified a car, a Ford Puma, that was known to have been in the vicinity when Lina went missing.

The vehicle was used by the main suspect in the case, Samuel Gonin, who died by suicide in July before he could be questioned. According to French radio network RTL, Gonin left a farewell letter, which reads in part: ” I have lost my honor, my dignity, my humanity, I must leave. I do not know how to control myself, it is going too fast.”

Analysis of his car’s geo-location data allowed police to identify several stops it had made, including the one made a day after Lina’s disappearance, that eventually led to the discovery of the body. RTL, citing the prosecutor, reported her body was found submerged in a stream below an embankment.

Post-mortem examinations, including an autopsy, will help determine the cause of death.

General Daoust, former lab director of the forensic science department of the French national police, told RTL that “even if the body may be very degraded, it will provide a certain number of answers.”