Missing Diana Quer's ex-boyfriend investigated over 'violent' threats and Facebook log-ins add to mystery

The youth in question has deleted the messages, which included a picture of a meat-cleaver, but police are still able to trace them.

At the same time, investigators are attempting to find out why the young woman's Facebook page shows as having been accessed at least twice in the last few days.

It had not been logged into since Diana went missing in the early hours of August 22 whilst walking home from the village fiestas in A Pobra, but suddenly showed her as having been online on October 16 and then again earlier this week.

The explanation could be that one of her family members, either at her mother's or father's homes in the wealthy Madrid commuter town of Pozuelo de Alarcón, may have used a computer where Diana's log-in details came up automatically.

But police have not confirmed either way, as they did very quickly when it was reported Diana had logged in to WhatsApp in the weeks after her disappearance.

On that occasion, she was showing as having been online because police had commissioned a duplicate of her SIM card to try to trace her last-known movements.

So far, the last signal before the battery ran out was in the location of a bridge over the river Arousa near the village of Taragoña, some 20 kilometres from A Pobra.

Sightings of the teen in the cities of A Coruña and Lugo, both at some considerable distance from A Pobra but also in Galicia, have been ruled out.

Diana's mother recently called for the search to extend to the USA, but her father was quick to dismiss the need to do so.

The couple, who divorced when Diana was 14, have far from an amicable relationship and their daughters, including 16-year-old Valeria, appear to have been embroiled in an ongoing tug-of-war between their parents.